I've owned several rear engined super buggies and I now own a mid engined class 1 Jimco. The Jimco, although heavier, has considerably lower polar moments of inertia. It makes the car easier to turn in and twitchier in the rough. It also makes it have a tendency to kick given a jump that rolls away at the top. Well formed ramps and the car jumps beautifully.
Tuning the shocks isn't as hard as some have made out. However there has to be compromises made. Either you have it good for smaller whoops or good for big jumps. Having huge bypasses may correct this. My 4 bypass 9100 series Bilstien's don't appear to flow enough bypass to cater to stop some of the fore/aft polar movements.
I also like the fact that in first and second gears weight transfer rear doesn't lift the entire front end off the ground (as it does with some of the other short wheel base rear engined cars).
Rear engine, high polar moments mean more leverage against the shocks, tend to disguise some shock tuning issues and allow a greater range of differing terrain to be taken.