I just installed my FAST clutch a couple nights ago and man what a difference a HD clutch makes. Honestly, I didn't think the 6 HD springs were all that bad, although its a big difference from the 6 stockers. Agreed, if you don't have a lot of HP, i'd recommend going the 3/3 route. Make sure you check your inner/outer hubs and basket, if those are worn bad it will only wear your plates faster. I got the whole package, excluding the basket for a couple bills.
Also, if you call Jeff, ask him about the shift spring mod...... It's a good one
Good luck...