@Carnivore: HP and BAB would be the obvious losses. You're still seven levels from your next iterative attack, whereas Scout 4/Ranger 1 needs only 1 level of Ranger for an iterative attack. Also, if your job is to skillmonkey, losing four ranks in all skills hurts. With +8 Dex, +6 Int, they're permanently a point behind any small, Dex-boosting race in all Dex, Cha and Int based skills except Hide and Search. Even with the racial boosts, they only break even on Spot and Listen. In short, if you want a skill-based build, avoid LA you can't buy off. Pixie rogue is a cute build, but it's not a skills-based build, which Swift Hunter can do easily, as well as damage.
Frankly, pixies are better at PvP than adventuring. In parties that aren't all pixies, their ability to hide, fly, and single-handedly win melee encounters isn't really fun for other players.