I had most of the same concerns as Sheppard has, and for mostly the same reasons, but i still voted "yes"on the poll.
Most concerns listed are not with dead=dead, but with the effects of (losing) rank. Since the rank-based abilities are not yet set, it may yet be too early to worry, annoying as it may be for the moment. To me, rank is way to much like an RPG level right now, which makes no sense to me. Is this really needed? Isn't being called General or Avatar-of-War already a reward of its own? There will be (I'm assuming) a social interaction component to GW, so the titles themselves are not meaningless (even if they are right now).
On a similar note, will rank even remain fixed on # of victories? Even if so, will these remain static limits, or could it be something more complex like "% of all victories by a faction" and/or "# victories in the last week/month"?. All those are possible solutions to get some social mobility going. Indeed, we need to prevent people from clinging to unto their seats too much, but this has nothing to do with dead=dead. If anything, death is a great promoter of social mobility (I just thought of something... an easy way to gain rank may be to tml your superior ). Ultimately, we could let characters die or retire from old age after a while, so that not taking any risks will get you only so far.
It is true that, in many other meta-games, long term motivation is important. But, is it really? I'm very happy I stopped playing the xp farming genre a long time ago. If at all possible, GW should be devoid of any such mechanics. I'm not so sure the typical RTS player is all that concerned with long term motivation.
Finally, I agree dead=dead will scare off some people, but I also think its worth to try it out to its fullest first. If it really doesn't work, then we can look into "dead=very annoying" or "dead=somewhat meaningless" options.