Among others, the Ripp product is discussed in these threads. Some of which actually include the guys from the Ripp company:
Not many folks around here seem to have them personally. However, there are other Jeep forums where more of the primary posters do. JK-Forum, for example. (Though they're liberal with banning folks, so be careful posting there.) Folks who install them seem to like them.
Any supercharger will obviously toast your factory powertrain warranty, but a Hemi swap would as well and there doesn't seem to be a lot of people complaining about damage done by Ripp's product anyway. Of the superchargers available, the opinion seems to be that Ripp has best deciphered the factory CPU such that the result is the smoothest and most "factory-like."
I have no idea what the 0-60 time would be, but it is undisputed that it adds A LOT of power. As I recall, it's somewhere in the neighborhood of 100 horsepower at the wheels and large increase in torque, including a doubling of the torque below 1500 RPMs or so. Thus, whatever the 0-60 times are for a stock JK, it would be quite a bit less with a supercharger. The Jeep would feel (and in fact be) much, much faster and more powerful.
If I had lots of money for discretionary spending, I'd have already dropped the $5k and picked one up. I'd also have tossed in the $2k for new headers and an MBRP exhaust, which would be much more useful in a supercharged 3.8 than in a stock 3.8.
I suspect many on this forum would do the same, though I'm sure some will disagree.