The Legion grips are modified G-10s, with little "patches" near the top on both sides (but they're different from one another) where your thumb and index finger come in contact. Someone also pointed out a small indent on the left side, toward the top.
In other words, they're tricked out.
And, compared to other 226s and the MK25 I've held, these grips seemed much more comfortable.
If, however, you decide to replace them with E2s, you'll have no trouble selling the stock grips, provided you don't want to hold on to them.