I have a male (7.5inch disc) and a female (6.5 disc) motoro, on a play sand sub, they are average activity i think, i can feed the male by hand if i can get to the bottom of the tank, they bury after a good feed for 30 mins or so, alot of activity up the tank sides and playing on the rocks, new addtion for them. But also bury a bit too, i notice they are totaly clean of sand first thing in the morning, i have one 2 foot 20 watt light for evening and another 4 foot 40 watt to go with during the day. Either way it doenst bother them with the activity.
I agree also that fish should be kept to as near as poss to there natural enviroment, for therte benefit of choice, not our being lazy, just my opinion.