Had an 8:05a res on Mon 4/18. We got in line for 7DM right after we ate. We were second in line which was cool. They didn't let us on until the park opened.
By the time we got done with our first ride, the rope drop crowd had arrived. It probably would have only been a 5 min (or so) wait if we had hopped back in line. But we opted to head over to PPF instead before that standby line got too long.
Our pre park opening res was definitely worth it because:
BOG is a very cool place and it wasn't very crowded; we got to wander around the Castle area and get some pics with little to no crowds; we didn't have to deal with the rope drop madness and were one of the first to board 7DM.