I think I'd go for a real Duemilanove at a knockdown price - my supplier of choice is selling real ones at around the same price as Chinese knockoffs on Ebay to shift them. Its still a 328.....
Linux has drivers for the FTDI built in and I can always put Optiboot on to gain the extra flash. I experimented with it a while back and I had one or two issues, I trust they've been sorted since its going into real production boards.