Jack, I had a 2" Rubicon Express budget boost and ran 33's for three years. I wheel my rig regularly and the only time I had any issues was when the sway bar was disconnected. The front end would flex and the tires would hit the top of the fenders, it trashed the seam between the fender and the flares. Also, the tires hit the sway bar. I run stock Moab wheels (stock RUBICON) but nothing too serious. I liked the low center of gravity and it wheeled fine but there is no comparison between the budget boost and the 4" long arm kit I have under it now.
No, I didn't regear. I have an '04 RUBICON, 4.0 with 4.10's. I don't have any issues with needing to re but when I put the longarms under it, I now have room for 35's. The reason I didn't go to 35's is because I would definately have to regear. Since my fuel milage already sucks, I decided not to.
Depending on what gears you have and tire size Yes regearing will improve MPG. Depending on the transmission you will recoup your overdrive gear. Personally I have the 6 spd and 3.73 with 33's I get decent MPG and still could use 6th gear and speed up in 6th at 65mph. On the highway 6th gear at 2250 rpm I'm at app 72 mph.