Shuttle gave me a real hassle about not returning a board to the vendor during the first year of warranty. I had to argue that I had no idea where the board came from (pulled it out of someone's home PC), and I was asking for warrranty service based on dates I found on the PCB. IIRC the board I was dealing with was an AK31 or 32. Don't remember which. I did ultimately receive a replacement board though.
Epox and Abit are pretty much tied for worst warranty service imaginable for motherboards. Epox has never, ever returned the three boards that I RMA'd to them (complete with $50 check for return shipping, which was cashed). Abit asked for original - not a copy - reciept, wouldn't do anything without it; wanted $35 for return shipping to fix a manufacturing defect (bad caps) and appears to have returned to me a motherboard with only about half its capacitors fixed, very possibly the same one I shipped them, based on the eight-week turnaround time.