Fluff and fair game mechanics most likely will never go hand-in-hand anyway... let's face it, fluff-wise for the technology they are supposed to have the Eldar ought to turn up to battle completely invisible due to holo-fields, kill everyone with barely missing a single shot due to advanced targeting systems, make some snide comments about the inferiority of their opponents architecture and pop off back into the webway before anyone even knew they were there. However, this wouldn't make for a very fair game.
Good luck with the project!