I think you would be more than happy with the 4600 on 4s. I run the same set up in my rustler, and I can only describe it as ballistic. The higher Kv works fine because the batteries dont actually put out 14.8 volts under load, its more like 14 volts. So the max rpm comes out to 64400, below the 65k limit. And thats assuming the Kv value is accurate under load, which as was previously stated, probably isnt. I dont mean to say the 8L wouldnt work, Im sure it would be a cool running torque monster, but I think you might be happier with the 4600s speed. Heres a video of my rustler that might help you decide. This is with a 9.815:1 overall gear ratio and stock jato 3.3 tires. I would guess the weight is pretty similar to your jato. I could definitely gear up to go faster, but it hit 55.7 mph on the gps as it is.