The grips can be replaced with any grip made for the P225. If you want grips that are larger, try some wood ones.
It takes a while for them to get made then shipped to the states. You also need to fill in most of the hole for the hammer pin on the left grip to keep the hammer pin from coming out. That takes a couple of minutes work at the worst.
For the most part the P6 is a P225. The hammer has a notch cut in it and they have heavier hammer springs which makes the double action heavy and are stamped P6. Those are the main differences. They are pretty good in my opinion to use as a carry pistol or just to use at the range. Magazines are a bit high in price.