Although I think there will be a difference in how the steering feels after the locker install , I don't think it will be as bad as you might think. The locker will rachet while turning , this will relieve strain on the drive train and the effort it takes to steer!
Yes, one wheel can
overrun the other in a turn, which means that the outside wheel will be able to turn faster, but if power is applied in a turn, the inside wheel will be pulling (when in 4wd) and trying to pull the wheels back to straight forward, or conversely, if in a mixed traction situation or traversing obstacles where one front wheel has good traction, and the other is on a low traction surface, or in the air, the wheel with good traction is going to try to rip the steering wheel toward the side with the least traction. I expect that this is why Torq-masters recommends against installing in a machine without power steering. When a manufacturer recommends against installing their own product in a specific situation, there's usually a real good reason for it. If you want a locker, install the power steering first. I'm convinced this is a safety issue first, but may have a big impact on the 'fun-factor' as well. It's gonna take a fair amount of effort and $$ to install the locker, and it would really suck to find out after the install that using 4wd makes driving the machine miserable, or worse yet, unsafe, without power steering. Maybe one of the guys with a p700 with a locker and no power steering (if there is such a thing) could give us some feedback on this aspect of a front locker??