RE: Beretta Xtrema or Rem. 11-87
I tried the xtrema out earlier in the summer and absolutely hated it. The fit was all wrong for me, which is consistent with every beretta shotgun I have ever tried. Granted, I could have had the stock modified and a bunch of other things, but with the choices out there, I see no reason to have to make any mods.
What you ought to do is a blind test. Go to a gun shop and with your eyes closed try out a few guns and see which one you think fits better and feels better. That should be your choice... assuming you have a choice. If your grandpa is set on getting you an 11-87 and it's going to make him feel good to do so, then let him. You won't be dissapointed.
Good luck,