The local fishermen run up the beach all the time at the beach we use in start bay, I've tried it in the past in my old Flatacraft Force 4 but not in anything bigger.
Its easier with a manual lift engine where you can just release the lock before hitting the beach.
Timing is obviously everything with hydraulic lift, as obviously you lose drive when the prop gets too high and don't get a decent run up.
RIBBED For extra pleasure.
Member of the ebay Blue RIB cover club.
Member of the Bombard 380 Aerotec club