the slipperential works like an adjustable clutch..which helps absorb some of the drive train shock. Wherether or not you need it or want it is entirely up to you, but, considering you are running 8s....
1. MBX-6 T8 1900KV, RX8 ON 4S
2. MBX-5T 1520, MMM ON 5S
3. MBX-5 ONROAD CONVERSION 1515, MMM ON 5S
4. MRX-3 ON ROAD CONVERSION 1512, MMM ON 6S
5. TEN T 2650 T8, MMP ON 3S