I just installed a tweecer r/t, and it is pretty cool. does everything all the internet sites said it would, to include presenting a mildly intimidating learning curve. Said curve isn't the function of the tweecer/software, it is the actaul tuning of the computer. Lot of terminology presented, you gotta figure out what you want to change and then decifer its nomenclature as presented by the tuning software. Fear not, the basics are out there, documented are the small tweaks to get you started as presented by the pioneers of self tuning. However, some of the big stuff you'll figure out on your own. Having said that, there seems to be a alot of helpful people willing to lend a hand, some are employed dyno tuners.
I think the tweecer is good stuff, never seen the other hot one, the Moates Quarterhorse, although I imagine it functions with a lot of similaritites. Either way, by going the self tuning route I'd get one first and play around with to get the hang of things. I can't imagine doing a whole HCI supercharger package, then tuning it to run perfectly by self tuning, and finishing it all by 5 pm Sunday and expecting to drive to work on Monday.
Good luck