I do have the Robust, with gas assist. You can raise and lower it almost without any effort. I rarely need to use it, but given the weight of the tailstock, it's great to have available when you need it. It stays well out of the way.
The PM swing-away is poor in all respects. Hard to handle, you definitely feel the weight when raising it, the screw locking mechanism is a poor design, alignment for sliding the tailstock onto the swing-away can be finicky, and it doesn't entirely get the tailstock out of your way. Given the weight of the tailstock, it's better than nothing but that's the best I can say. I've owned a PM -- it was essential to have the swing, however problematic -- and frequently turn on them away from home. I've never used a Oneway swing.