For pure bench use I would suggest a rear grip. It gives you the ability to get a great trigger like a Jewell (lighter pull, faster lock time, etc).
For a dual purpose SP I prefer the center-grips.
You can get a extremely light trigger pull with a after market center-grip trigger & linkage (no safety) made for an XP. I have never tried one yet myself.
If I use a long eye relief scope it is the Burris 3-12. All of mine have the ballistic plex reticle and most have target turrets, at least on the vertical adj.
I have three rifle scopes I use on my SP's
The Leupold Mark 4 8.5x25 you see on my 7mm Dakota that Kirby built for me. Burris 6-24 Black Diamond (30mm tube)and a another Leupold Mark 4 6.5-20.
Richard Near makes pic mounts for the XP and have his on all of mine save one which is a Farrel.
It would be interesting to see what can be done.
The 7 Dakota
w/ Richard's 200 WC (BC approx .83) @ 2706 fps is a wind eating bullet for a specialty handgun at LR.