I found the shorty car pretty useless on the bumpier tracks. Saddle car was far more comfortable to drive.

Maybe the track that i predominantly run at (Bury) isn't as bumpy as other tracks

Noticed a bit of rear end bounce myself at RHR, but had also done with my carbon chassis when I tried that.

I stuck the rear balance weight in, and it was better, along with the 2mm rear roll bar.

I'm going to keep it shorty for my first Worksop, and maybe try York indoors. see how it is there, before I swap it back, but so far much prefer the saddles car. I guess its safer and more planted, but suits me.