Picked up on the rumour that something in the thermostat is pressure sensitive, so if you do rev 'em a little bit some coolant is pushed past it, meaning that the stuff in the rad is warmed slightly too, reducing the thermal shock bit. So better to drive off and warm it up on the move, rather than leave it warming up whilst you finish closing the garage, fiddling with belts, putting on mascara/lipstick, etc.
MAV put my donk back together after it had been soundly neglected by it former owner, replaced the plastic dowels, putting on a new land rover gasket and head bolts, etc, replaced 'stat with an 82Deg item, and it did not miss a beat for the next 10k miles, no need for a coolant top-up or anything, and it was never warmed up on the drive.
Don't know if anyone has an opinion on the above, but it worked for me.
BB