Thanks Jeff for taking the time to explain your setup in great detail, it was very informative. I've tried several sofware based effect and amp simulators, and I've found (as you pointed out), a good quality interface for your instrument and some kind of hardware controller are a must.

You also need a decent computer, especially if you are planning on recording at the same time you're using theses sims.

My personal opinon is that for studio work those sims are great, but for giging I would prefer to use a standalone effects system such as the Digitec RP500.