the 11-87 and 11-87p are comparible, much like the 870 and 870p, not a monsterous difference, just a little beefier parts, internally, as well as i believe the P comes stock parkerized, were the regular doesnt, but in the case of the 870, i got the HD and i talked to guys who carry that same model in alaska, and they have never had a problem with the finish. Hope that helps.
Tim