100mm Macro + Reverse 50 OR MP-E 65

I own a 100mm Macro lens and an MT-24EX flash unit.

Ive been enjoying macro more and more, but have not had a chance to really play with magnification greater than 1x.

I've been looking at all the awesome reverse 50 shots, and shots using 50 and tubes along with a 100mm macro.

If you (I) can afford a MP-E 65 macro lens, would you even bother using reverse 50 1.4?

I also have a set of Kenko tubes, and a 1.4x TC. I plan on buying a 50mm 1.4 regardless. Should I just skip out on the MP-E 65, or is there really no replacement for a lens like this?

Just trying to get some insight as to what to use, and what type of magnification I am going to get with all the above setups.

Other question is if you had both setups... would you even use the tubes, or just sell them?

well having the MPE65 I can say I wouldnt bother finding any other way to reach x3-x5 magnifacation, its just too convenient and a high res lens to boot. You could get a second body and have the 100mm macro on one for full body shots of larger bugs and the MPE65 on the other for the tiny bugs and ultra closeups.
Keep the tubes though.