I use hi tec all the time Trevor, as do a lot at our club, find them very reliable. Not too keen on the karbonite geared ones, on big stuff I use metal gears, never used the 125 so cant comment but they are lowish torque, 625 or 645 have much better torque will take 6 volts and fit in wing no bother, or you can spend a bit more and get digi's,
look them up at Steve Webbs it gives all info, and shop around you get good deals, Leeds model shop has been doing a good price on them.
John