I love Ritebrew. Love the grain selector to buy ounces, make my own recipes (okay, shamelessly pilfer and copy HBT recipes), Neil even has a double crush option for us BIAB-ers, and with shipping it's still cheaper than my LHBS. Love them. Awesomesauce.
[Edit: oh, but in answer to your actual question, no, I've not tried the kits. Bought plenty of grains, hops, yeasts, hardware and root beer extract. But not the kits]