The plan would be to eventually find a set of Miata BBS wheels to mount 205/50R15 Hoosier A6's so I'm not too concerned about having to run r-compounds. My 2 is my daily driver and while I don't mind coilovers, etc. I do drive my wife and 7 month-old son around a lot and I don't think they'd appreciate them. I figure with H Stock the only "permanent" mods would be the rear "swaybar" and adjustable struts. Everything else can be easily removed for daily driving. The mods allowed in STF are much more comprehensive and I feel I wouldn't be competitive unless I make the car less roadworthy and my RX-7 already fills that void. I'll checkout the Cinci SCCA a little more to see what classes they run.You should see if your club offers a Road Tire FWD class. No matter what you do you will not be competitive in HS until you buy R-Compounds. RTF allows you to use high performance summer tires like the BFG Rival and Toyo R1R.
STF really isn't that bad, and participation is much better (at least in my region). Get tires, coilovers, and swaybars and you'll be regionally competitive.