Originally Posted by qqy
You can use a standard double derailleur, but I've read a number of reports of the chain falling off the 34. It could probably be avoided by playing with the low limit screw, but I really like my FSA c-16 compact front derailleur as it's basically idiotproof and I had no trouble installing it myself.
The limit adjustment won't fix that. You can buy a chain keeper that attaches to the seat tube and prevents of chain from going inside the small ring.
I use an FSA SLK 50/36 with an Ultegra regular FD and it works like a charm. I do have a chain keeper as described above and it has prevented the chain falling off the small ring completely.