For the money Id go with the Smarty jr. a little cheaper then the Edge EZ (although the EZ is still a good prduct). But if your willing and have the funds to support the habit, go with smarty sr. and be prepared to spend tons to up grade engine and transmission to go with the smarty sr.
pros to diablo... hmmm have one makes a good paper wieght!
cons: support... none makes my truck run like cr@p! engine surge, rough idle...
hypertech... note key letters "hyp... "
Smarty jr or Edge EZ for mild gains better then the two above, with like I said, smarty being cheaper, my choice would be smarty jr.