A true SSD, 2.5" IDE or SATA (via adapter) form factor would likely be a complete waste of money for an A1200. You're still going to be fighting the slow native IDE interface of the machine.
Benefits of a CF solution are the fact you can simply pop new CF cards into the machine to boot different configs, and along with that use said CF cards with an inexpensive add-on USB card reader on a commodity machine using UAE to set them up. The internal 2.5" drive you'd have to remove each time, where as a CF card you can just pop out if the mod is done right. CF solution is a hell of a lot cheaper, to boot.
I have SSD's in all my machines, using RevoDrive's in my PC's lately. Got a 32 GB Patriot SATA SSD in my SAM 440 machine that works extremely well, but then again it's native SATA onboard. Machine boots from cold to ready to use in a matter of seconds, was really a stunning difference when I put a SSD in it.
Depending on your views on SSD tech and the accompanying OS's, many people dislike using SSD's on any machine that does not support TRIM - which AFAIK, the Amiga does not.
