Quote: @jmg257: glad to hear you the 55-300 is capable. It would be nice to have that kind of range shooting outside sports; though I am guessing it is a little slow.
If it makes you feel any better - If you do decide on a K-5, the 55-300 is a nice lens for outdoor sports. I have used it for the last 4 years on "fast" sports (high school soccer), and "slower" sports (high school baseball & major league baseball), and it has performed fine. It's nice to have the flexibility of a zoom for sports, and if you work WITH it's limitations (I.E. speed) instead of fighting them you'll be quite pleased. For example, when shooting my kid's games, if the weather is grey, or it's a night game, I'll concentrate less on getting game-action shots, and use that as an opportunity to get shots like the players interacting on the bench, the coach taking a player aside for a talk, players waiting to go in or in the on-deck circle, group shots, etc..
This method ensures every shot doesn't look the same (I.E all game-action shots), and it allows me to be quite happy with that lens instead of fussing about how it's not fast enough. And frankly, when the kids see all the shots - with the exception of the rare game winning goal/homer - their favorites are usually the candid ones outside of game-action, where there was no need for a 2.8 lens.
Hope that helps,
Tim