I have 3 security six's, a redhawk, a super redhawk, and an old army.
They all have aftermarket rubber grips.
Some do have Pachmayr grips, but the ones that I use the most (the redhawk the super redhawk, and one of the security six's) have Hogue grips on them.
See
http://www.ajaxgrips.com/ajax/hogue?set=03The Hogue grips do not cover the backstrap on either redhawk, so the felt recoil reduction is not all that significant. There is some, as both metal and rubber are in the palm of your hand. What I like best about them is that they allow you to get a better grip on the gun and it will not shift around in your hand. I shoot bowling pins alot, and the game is pretty much over in under 3 seconds. You want a good grip for recoil recovery. You don't want the gun sliding around as you don't have time to readjust your grip. One a hot day your hand gets really sweaty and the Hogue finger-grove grips work really well for hanging on.
A "PAST" shooting glove (which I use alot) will help reduce pain if you are shooting hot loads alot. The redhawk and super redhawk are both magnaported barrels. Magnaporting a pistol barrel reduces muzzle climb to get back on target quicker. Magnaporting DOES NOT reduce readrward recoil. In fact, it increases it. You will feel the recoil in your sholder increase significantly if you Magnaport. Having said that, with either Magnaported 44, with Hogue grips, and with PAST gloves (at least one in the strong hand), recoil hasn't really bothered me much. Both guns have mounts with Pro-point sights on them... that adds to the weight and helps absorb recoil a bit.
Compaired to the gun, grips are cheap... buy a couple different ones and try them out. Everyone's hand is a bit different sized, so what works for one person may not work for another person. If you have a local dealer who believes in good customer relations that has several styles in stock, see if he will let you check them all out. I am pretty sure that Ruger puts the cheapest grips on their non-rubber-gripped guns so that you don't pay extra for something that you are going to trash and replace anyway.