I had the HemiFever tune with the stock t-stat and eventually ran a 180 as per Sean's recommendation. We're in that time of year now up in the mountains where it's 80 during the day and down to 40's at night. The main difference I've noticed with the switch, other than a slight increase in perceived throttle response, is fuel mileage with MDS off in the warmer weather around 45-55mph. Best I got with the stock stat was 22-22.5 being light on the throttle and coasting down the mountains as much as possible. With the 180 I, very surprisingly, have seen 22.5-23.5 which blew me away. I didn't even know she had it in her! I think the key, as it's already been said, is that I'm running a tune that is calibrated to run with the 180 stat.
All that being said, I am glad I made the switch. I was planning on doing a few trial tanks and then taking it back out. But it's been 1,000+ plus miles and I still haven't considered going back to stock.
Just my 2.5 cents...consider the extra .5 a bonus.