[yellowjacket]

IF your scu is load reactive and IF your caster is set up correct, you should be able to let off the wheel after a turn and the steering will self center, just like with mechanical linkage. if you have a non load reactive scu, it will "lock" in place whearever you take your hands off the wheel, regardless of caster. also, non load reactive will not provide the steering "feel", like when your up against a rock, you may not know it strictly by the steering feedback.
i hate non loadreactive scu's because of the return to center problem you described, and cause its so easy to break stuff since your just turning the wheel, unaware that your front is pinched between rocks.

i never had a problem with a single ended ram in the past, but i put a lot of effort into matching up the components. currently running a psc double ended ram, though for different reasons. sorry im not more help

hows your caster?