I have been thinking about this and I think I would avoid QFN (quad flat no-lead). Without an x ray machine, there is no way to inspect the component after reflow, so there could be bridges you would never see. If there are bridges, the only way to fix them is to remove the entire chip. Since it has four sides, removing it, even with a hot air rework station, is going to be a challenge. And then, how do you get it back on without disturbing the neighboring components? You can not hand solder it, because there are, well, no leads. And, assembly houses charge more if your board has no lead components and/or fine pitch components (but FTDI chip is not fine pitch).
I have been told by many people that swelling the apertures works well to solve the bridge problem. The FTDI chip does have tight leads, but they are not technically small enough to be referred to as "fine pitch." Without swelling the apertures, I got bridges, but I was able to wick them up and all was fine. I doubt I could do that with QFN.
Just my 2 cents. On the other side, heck, I'm willing to give it a try! Maybe I'll be pleasantly surprised!