I just got a L3901 and I'm going to put a 3rd. function on it. I'm trying to decide between the WR Long and the Summit 3rd. functions. One difference I see is the Long has a rocker switch and the Summit uses two buttons. The prices I'm seeing is $840 for the Long and $600 for the Summit. Is there any reason to pay the extra $240 for the Long unit? Is it better in some way?