I've had my Gaoersi 6x17 for about 3 or 4 years now, much of the time I have to use it hand-held so shoot 400 ISO film. Delta 400 means I can shoot at around 1/125th f16 or f22 much of the time.

Like David I find the helical focussing is fine, with a 90mm lens or wider then using the Hyper-focal distance works well, particularly when you can stop down reasonably, I'm actually using a 75mm Super Angulon on mine which gives a touch netter DOF/