If you go with the Ram X-Grip, just be sure to tether or strap in your phone. I have had my 4s ejected from the grip 2x now in about 1,500 mi of use. First time it hit the ground at ~45MPH (it survived but the back is shattered). The second was at ~65MPH, but luckily was on the charger and the lock in cable connection on the older 4s phone cord saved it. I now only use it if tethered on the power chord or add rubber band straping it to the holder.
Is a very nice mount, but hard to recommend for MC use given the phone/GPS it holds can be launched out. Both times for me were result of had jarring type impacts. Not your common bumpy road / vibrations as the phone/gps stays put and I have never seen it move or slowly work its way out. Things like very large seams or gaps transitioning road surfaces at bridges and the like can send it flying out.