One thing I would say is this: trust people.
Sephany's player mentioned our roleplay together, with myself as Miriel. Whilst the constant battle was probably annoying to her, I tried to conduct myself ICly. Sometimes I would get the upper hand, sometimes she would. But because I trusted her player not to always codekill, I could roleplay with her without fear. Now, I do not mean to say that I would not have hunted her down ICly had I been OOCly afraid of dying - not that. I am prepared for my character to die. But when you find a RP partner who knows how you prefer to do PK, then everything flows. We had a few moments, where we paused, and one of us would ask: "Erm... can you do that?" The other (either one of us) would say, "Oh, actually thinking on it, probably not."
There are a few times when I haven't said anything about what I see as OOC slips in PK rule, because the RP is still good. e.g, the rule about five rooms away. Sometimes, I know someone who has come to harm me has been more than five rooms away, but do not say anything because I would rather the RP - however... I play almost exclusively goods. I understand that the five-room-away thing is important to protect people from being mobbed, so I am not knocking anyone for checking about the five-room thing.
So, my main point here? Trust. If you trust the player to type in the correct killmode, and not doing the usual, "Oh, god, sorry, had killmode kill on accidentally." then you can RP with more flexibility. Personally, I hate code death, but if in the two seconds before combat, when you decide what mode to go in, they say "I think this should be code death" I am fine with it. As long as it is RPed properly, and makes sense. For example, if it was to be code death, I would make sure that it happened in spar, so my wizard could take into account the fact that she is flying, and the lowly fighter that could kill me within seconds on the ground, is not.
Is that power-gaming? I would say not. If I was a fighter, and a mage was flying (it has happened, in my sporadic flirtations away from wizard characters), then I understand that I get what is coming to me. I trust the other players to RP rightly, and to understand the IC situation. Occasionally, that trust is misplaced, and that has happened to me twice, in perhaps three years of playing. That has never in my case been followed by my making a complaint to the imms, but rather a brief otell saying, "What?!" and then after that initial anger at something that was completely ridiculous, reasoned with the person and yes, gone back to RP with them again.
(Unfair in this case being lack of RP before the death, or use of summoning spells without warning, or something I see as ICly possible, but OOCly pushing that limit to extremes - give someone a chance to RP, that's my motto. A wizard flying about a fighter, raining death can be roleplayed well from the fighter's perspective. A wizard summoning in monsters and then typing "order wyvern w" does not allow a fighter any form of roleplay, other than dying)
So, after this rather long and disjointed discussion on PK and RP, I should probably link it to competetiveness. I think most of the competetiveness outlined above comes from the ease in which we die during PK. I know that OOCly, it really irks me that some wizards, who know what to type and when, can go into really dangerous areas on their own, killing things with ease, whereas my wizard nearly dies from a low-level mob. But I keep that OOC - competetiveness, yes, but why should it bother my character? The same goes for when I see one of my ranger comrades with a new piece of nature-like armour, which would look REALLY good on my character, and I think: why don't -I- have that? But again, it stays OOC (this is me being VERY honest, by the way - again, showing TRUST... like my link, there?

)
I say competetiveness is fine, to a certain extent: it is a game, and games are so fun for the main reason of advancing your character, and watching them grow. The competition comes from seeing others grow, and then moving your character against a character of opposing views and fighting (crude simplification of RP, I'll admit). It's only when OOC competition that I outlined above turns nasty, and affects you IC. Let me give an example (which has no basis in fact):
Miriel is REALLY jealous of a certain ranger, because they are higher in her faith than her, and OOCly her player thinks that why isn't he that high? That's not fair, I've been on for three years! Count them and see, three entire years! So OOCly, the player starts making IC investigations into his character's faith brother/sister, and FINALLY uncovers something which is not nice about them, reporting them to their faith manager (with some OOC glee, whilst being ICly very, very sad), and watching them get demoted.
That is competetiveness. But very, very, very bad competetiveness. It stems from OOC jealousy, and has not basic in IC fact. Why would Miriel have suddenly become suspicious of random faith member? Any reason? No. It's unfair, and horrible.
However... if Miriel was to walk into a room, and happen to see a drow in conversation with one of her faith brothers, and then decided to watch that person, and then realised that that person was secretly worshipping Lloth, then whether or not they are higher than me in rank, whether or not there is some chance I could be jealous of them OOCly, by the gods I am telling my faith manager and having them demoted, and hopefully killed. In that case, IC actions are not led by competetiveness and so are in this case good.
To finish a long post for which I am eternally sorry - I doubt many will read it all

- competetiveness not neccessarily bad. Competetiveness is what makes us log on to FK, at the basic route. Letting that competetiveness influence your character in ways that character would not logically act (btw, as long as YOU know your character would act in that way, it doesn't matter what other people think - within reason) however, is imho, a bigbig nono.
Hope something in that makes sense, because I'm not sure I said what I meant to say when I first read this post. I kind of just... dribbled on and on.
~Ol
PS: I used the example of my character in this. Any example of her doing any specific things in character, such as faith brothers and drow, are not based on any RP, on any players, or on any events that have happened. They were created to put the issue of competetiveness into context. Examples of me -really- -really- wanting a ranger's new piece of equipment however are, regrettably, true. I hate to see better-dressed characters than me.

Examples of my being jealous of faith members who are higher rank than me are most definitely not true - they've earned it.

If you have knowledge, let others light their candles with it.
--Sir Winston Churchill
"This place is boring, I'm gonna go eat whatever I can find laying on the ground"
-- Hoildric
Cacie asks Larethiel 'Did that air just bow to you?