I've hardly used my K-3 since the K-1 showed up. However, after getting my 300 last Christmas, I've been promising myself I'd hang it on the K-3 and go stalk some critters, since that combo seems better suited to photographing wildlife than are the K-1 and 300. Today - sparked by a conversation on one of my earlier threads - I actually got off my behind and gave it a try. I chose a local pond that often is populated by gulls, ducks and geese (or what I think are geese) to experiment. Here are three shots of a (putative) goose; the first one is uncropped while the other two are cropped slightly.
It was an ergonomic pleasure to hold and use my K-3 again; I've never particularly liked the bulky feel of the K-1 or do I care too much for its control layout. However, I have to admit that the K-1 does a better job of balancing the heavy 300, and I was surprised how tentative the AF of the K-3 feels after using my K-1 for a year and a half. Still, there's no doubt you obviously get more reach with K-3/300. I'm not motivated to concentrate my photography on wildlife, but when I do want to venture forth specifically to shoot some critters, I'll take my K-3.
Jer