Welcome to the BeerSmith forum. Like Kevin, I built up from extract to BIAB to (though not a shiny system) a three vessel system. I quickly moved back to BIAB inside doing 10 liter batches as it allowed me to brew more often and more styles without burying myself in beer. I now have an Anvil all-in-one system which is still based upon BIAB but gets me out of the kitchen (to my wife's delight) and away from propane. Also started doing 4 liter batches as a test bed for developing new recipes without the worry of having a whole case to work through of something that was not quite up to what I wanted.
My one piece of advice when starting with BeerSmith is to take the time to develop good equipment profiles. Treat the profiles which come with the program as templates for developing your own. The more measurements you take during a brew day and updating of the boil off rate, grain absorption, process losses, and most importantly your efficiencies the faster you will bring the software in line with what you produce.