I can speak of the Quad-135 tuner, although I have only ever run it in the 110 setting (I didn't care much for the 70 & 90 settings). I can tell you in the 110 setting, it's night and day difference, plus an extra 1MPG or so in the city! It's hard to believe until you have one and use it for yourself, then you'll see.
I recently had to take mine off for a trip to the stealer and holy $hit what a difference!
I also don't have gauges and have not made any other performance modification (yet). I plan to get an AFE-2, 4" exhaust, and gauge set rather soon I hope. I don't tow anything, and there aren't too many grades around here to go up, so I am not worried about the EGT's. Once I get gauges, I'll try the 135 setting.
The only negatives I would say are the 2000rpm surge and a little extra injector noise/rattling. It's worth it for the power gain.
I bought mine from Van Massey a while back in a group buy Mike setup. I would recommend buying from Van.
Tim