NsideLine

That sounds about right... I run Losi oil, like Chad does, but I've tried going with the stock 1.4 pistons in the rear, and you just need to thicken up the oil a bit but it works fine. He runs drilled out 1.35 pistons, and that's what came with on mine (I got the pro-built version), but I changed out the rear shocks with a set of pre-built units I had built for hot weather with thicker oil, and then someone swiped my shock parts box containing the original rear shocks, so I no longer have the ones that came on the car with the 1.35 hole pistons in them... (Damn thieves!) But I've found 1.4 work fine, just raise the thickness of your oil 5 wt. or so...
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As far as the center driveshafts go... They really don't wear that quickly. They just need to be changed out during regular maintenance intervals as described by the manual/common sense. They won't last forever, or maybe even as long as all-steel universals, but when you want the utmost performance, and a lighter drivetrain is in order, you really need to weigh the benefits//costs. I've found they are more than durable enough to last through a few months of solid racing every weekend or every other we. So, unless you are a noob or just expect to never have to replace a part on your car unless it breaks... etc... Just maintain it, and don't complain, or get the steel uni's they have available and sacrifice a few grams to gain durability. The rear shouldn't scrub the engine mount and/or the block unless you are using the wrong gearing/the one-piece engine mount, or have an extraordinary mill that sticks way out at that spot... I have used the stock two-piece engine mounts and it had plenty of clearance, and am now running the one-piece mount and have had it rub, but ground down the block slightly on the corner and now it clears fine. This should be an easy fix, so if it happens, fix it, and go on racing...

-J