I have done some A3 prints with lenses such as Tamron 17-50 f2.8 and Sigma 70-200 f2.8 EX DG II and there was absolutely no problem with image quality. I believe the Ltd lenses from Pentax are even better image quality again.
I am very happy with the Pentax system and eagerly awaiting my K7 body. Unfortunately I can't afford the good Ltd lenses right now but like yourself am keen on a wide angle prime, perhaps even DA21. I would love the FA 31 Ltd but need to do a "bank job" first
FWIW, you might even look at re-purchasing some of your old lenses from ebay. I have had experience with a few older Ricoh, Pentax/Takumar and other Jap-brand lenses from back in the day. You can still get superb image quality on modern digital SLR cameras. My friend has a Super Takumer 50mm f1.4 almost permanently attached to his Canon 5DmkII and the image quality is outstanding, even considering the full frame coverage at 21MP.