Originally posted by surfar I don't own the 17-50 or the 35mm
I would strongly echo what others have said: Wait on the FF. It will serve you well when you do get it, but filling out your FF lenses will be easier now than after spending almost $2000 on the K-1. It would also make finally owning a FF much more rewarding when you have some good lenses for it!
I've had very good luck purchasing here on the forums - maybe not so much luck, as just having a great community to buy from! The DA 50 is considered "mostly FF compatible" but some say there are small bits of vignetting - it might be worth a bit more investment and get an F or FA 50mm 1.7. It seems that it is one of the favorite versions of the 50mm around also!
On your flickr it looks like you do some macro work, and the DFA 100mm macro would suit you very well, and there's a WR version also! The Tamron 90mm might save on some budget, but I think people like the DFA better in general, and it's been going much cheaper these past couple months than it was a year ago!
I'd also look into an F/FA 28mm, the FA Limeteds as mentioned, or possibly the DA 40 Limited and DA 70mm Limited, as both do well on FF! The F/FA 135mm f/2.8 isn't a pretty lens physically, but it's great for portraits on FF (but if you get the macro, you'll have that range almost covered). The DA*200 and 300s are amazing on the FF also!
Last week I tried my sister's 55-300mm on the K-1 and was amazed at how little vignetting there was! Mostly just noticed it at the 55-70mm range, and zoomed in to the long end I didn't really notice any! I didn't do any official tests or take pictures at the different lengths, but it seems quite usable!
Best of luck! I really think you'll be happier buying a few more lenses, and the K-3 is an amazing camera for sure! Who knows, spend the next 6-12 moths watching for some lens deals and you might get yourself a nice bundle deal on the K-1!