The 3905 diffs have held up to my brushless E-maxx, been beating it for a couple months now.
FWIW the Hybrids can be done for less than $260, I'm in the process of upgrading my truck with FLM Hybrids, Hyper 8.5 diffs, and the goodies from RC monster to use my stock 3905 drive shafts and the total cost was $225, still pricy but I'm getting some nice upgrades!