You can only switch to PCB mount if the PCB supports it. I don't see any real difference between plate and PCB mount stabilisers, at least none that really matter. The sliders are fairly loose in the mounts, so they aren't affected much by being plate or PCB mounted. If you bottom out the stabiliser sliders, then plate mount could be a touch more stable, since the mount point is higher and the plate is more solid than a PCB. On the other hand, the PCB mounts tend to be very snug and some plates are not so precisely made, so the stabs could move sideways a little. So it all depends, but I don't think it really matters much as I said since they are both very stable vertically which is most important.
Clipping the tabs allows the stabiliser to bottom out instead of being damped in the last 0.5mm of the movement. I like the damping, but I think I'm definitely in the minority about that.