Idk, I really try to avoid pro stock anything. You don't have any idea what the build specs or custom alterations were. If you can see them in person, great. SidelineSwap? What do you do if you receive them and they absolutely won't work?
In general the Nexus pro stock should provide more build quality and protection than the S29, but will they fit? The S29's can't have much to offer. I've got a pair of 2S Pro pants here now and they're not super impressive.