I have shot PSS's a bit and can tell you some base info. The rifle is quite similar to their VS or varmint synthetic, except a slightly different HS Precision stock is used, a different finish and they have a second sling swivel stud on the forearm. It is a big rifle, not light and usually very accurate.
The stock is good as is, it has a slight palm swell, believe it is pretty similar to one used by U.S. military so it is proven tough. You get a very good stock with the PSS, all you would need to do is apply a bit of bedding (skim bedding) over the aluminum bedding block to ensure a perfect fit of the action to the block.
We found that the finish (sort of soft, Parkerized I believe it is called) marks easily, but that is not a big deal if you intend to learn about LR on the rifle and then have it rebuilt when it is shot out.
Some people argue that the VS is just as good for quite a lot less money. Slightly different stock, no palm swells but still stout, one less swivel stud, brighter finish, not sure about barrel contour but probably similar dimensions. Have shot some VS rifles that are excellent right out of the box, but same goes for accuracy of the PSS in most cases. After a break-in session which probably does more for the owner's confidence than for the rifle, I have seen several VS's shoot sub 1/2" for five shots at 100, these were all in .308 Win. caliber.
The used Styer may be a very good rifle, but even used it will be pricey. In most cases a person does not really know how it was maintained, how many rounds are actually through it, or how hot the barrel was allowed to get - that can be a bugger on barrel life.
Have you considered the Win. Stealth, like the VS/PSS it is also a great LR rifle. The WIn. loading area is bigger than that of a Rem. (more open) so easier to get rounds in and out. Also makes the basis for an excellent custom rifle
, particularly the pushfeeds which many guys don't think are as good as they really are. I have shot many M-70 pushfeeds that will shoot as well as any M-700.
Good luck with your decision.