I load 45 colt, and started out using the FCD. Then I got my seater die adjusted so it crimps, and I don't use the FCD anymore. I did not like the feel of the FCD (rough), and it is one less operation to seat & crimp at the same time. I use Hornady dies.
There are a couple of reasons why an FCD might be better than crimping while seating, for straight wall pistol cartridges. If the cartridge headspaces on the case mouth, like most straight wall rimless semiauto rounds, and/or if the brass is not trimmed to uniform length, then the FCD may be useful. Also if the bullet does not have a canelure (crimping groove). Finally, progressive loading may run smoother with an FCD to iron out any buckled cases should they occur. This is a symtom of a misadjusted crimping die, and/or non-uniform case lengths.
The bottleneck pistol cartridge FCD also uses a collet (and no carbide sizing ring) like the rifle FCD, but is built on the Lee collet neck sizing die body, not the rifle FCD body.
So, if you are reloading a cartridge that uses a roll crimp, and make sure your brass is of uniform length (does not require trimming every time), then crimping in the seater die is pretty simple to set up anyway, and save yourself some time and money on a die you don't need.
I have not been impressed with Lee seating dies either. Of the dies I've tried, I like Hornady best, RCBS second, and Lee third. The forster and redding competition seating dies are similar to the hornady (possibly better), and have excellent reputations. The hornady dies can take an optional micrometer adjuster too. They are also simple to disassemble & clean without touching the settings, even on-press if need be. This is especially helpful when reloading lubed cast bullets.
Andy