I am using the standard chassis. I haven't run mid-motor mainly because I run on outdoor loose dirt. You are correct in thinking in RM configuration the longer you make the wheelbase the more traction you gain. You also gain more stability when jumping. The trade off is, the longer you make something the more difficult it is to turn. I feel like I have better traction in my current configuration with the stock length chassis. Rear motor 4, flipped arms, and I have the hubs all the way to the rear. This is the longest possible wheelbase you can gain from the stock length chassis and it gives a very stable ride. After I swapped the arms and shifted the hubs the buggy became easier to drive out of corner's and i noticed it was more consistent going over jumps. I found I was less worried about lining everything up perfectly.. The buggy became more forgiving.