and if you don't want finger groove ones, try these:
http://www.pearcegrip.com/Products/Colt/PG-OM2
The only problem you will most likely run into going with either one, is that you will most likely need to acquire full length 1911 grip screws. Remember, the RCS model (both the all black one and the two-tone one) comes with thin grips and thin grip bushings inserted into the frame (which means you currently have thin grip length (short) grip screws). You should be alright keeping the thin grip bushings (shouldn't have to change out the bushings), but will most likely have to get some normal full length 1911 black allen head grip screws to accommodate the normal thickness of the rubber grip panels. Hope this helps.
I have the two-tone Sig 1911 RCS model myself. Great pistol. Good luck.