Maybe this is like comparing apples and oranges, but I have a B7800 with the LA402 FEL and filled 8.3 x 24 rear ag tires. I run a 6 ft. 3PH blower and have had absolutely no issues with balance or traction.
If rear snowblower weighs 500 or more pounds. You should have no problems with counterweight. I use my <font color="orange"> Kubota </font> weight box or 6' heavy duty rear blade for counterweight when my 6 1/2' Curtis blade is on. Rear blade weighs more and gives better traction to rear wheels.