Scouser

I haven't really had to touch the diffs for months. I do strip down the gearbox every couple of months to check it all out and have a look at the diff while it is out but never had to do anything to it. Glad you like the Atlas diffs. Mine have been raced for approaching two years now and still look like new. Probably the best upgrade I fitted to the car.
As for the bearings, I clean them when I break the gearbox down but I got two sets of upgraded ones ages ago and just swap them around. Not really needed though as the bearings have never been a problem, still smooth as ever. Bear in mind though that I race indoors on carpet rather than dirt. If I were racing outdoors I would be doing maintenance far more frequently.