I have a G1570M, and I don't find it hard to lock down. If anything, it tends to be a bit on the stiff side, so it works better with a heavier, larger camera than with a smaller camera.
Majestic heads are pretty stable for a large camera, and they aren't too expensive, particularly if you find one second hand (and even more so if you buy one that is designed to clamp onto a tube--you can buy a 3/8"-16 adapter for those from Bencher, which currently sells Majestic). The tilt and pan tighten fairly easily, and the fore-aft tilt is geared, so it's self-locking. I can point my 8x10" Sinar P parallel to the ground for copy work, and it doesn't move.