No one is saying the Prostaff's aren't durable. I haven't read that any. I will also point out that I haven't seen many complaints about Burris not being durable either. So I'd go with the one that offers better clarity, better in low light, and better features like better adjustments that you can turn with your fingers out in the field instead of having to have a screw driver or coin. If you look into that Burris is the clear winner for not much more. Both are durable so I doubt you'd have a problem with that with either one. If I really wanted a Nikon I'd step up and get the Nikon Team Primo's.
The posts on here from Prostaff users seem to be saying theirs is durable and great because it holds up. How many of you have actually owned other scopes like a Burris or Vortex and can honestly say the Prostaff is clearer? Nothing I've ever read or seen has indicated that the Prostaff is clearer or better in low light than a Fullfield II.