Welcome to the forums
You were most wise to go with the RSST, I was dumb enough to go with an AGA-T2 for my first RBA, even though I was told about the RSST by a friend in no uncertain terms beforehand. I started vaping back last July 2nd and in six weeks was building RBA's and using a mech. I build my RSST with 400 mesh and 26 kanthal now, vaping at .7 ohm and I'm pretty darn happy with that. I make my own juice too, and if you haven't started that yet you should. Saves you a bunch of money, I'm not kidding!
Also, take note, the juices you sample in your B&M's testers will not taste the same in your RBA when you get it home. It's really best, I have discovered, to make your own juice for what you will be using it in.