one more prop question

[2182]

so i started out w/ a 14" by 19 pitch, was getting 36-37 mph at 4000 rpms, which was phenomenal(w/ a medium load). problem was i couldnt break 5050 rpm (at 40 mph, light load). so i went to oswald propellors (great guys by the way) here in charleston, told them what was going on, and got a 15x16 prop for her. now i am getting 5600 rpms, which i wanted (and 44mph) but at 4000 rpms, boat runs 29 mph. so my thought was go w/ the original, trade the 3 mph top end for a 37 mph cruise anyday. prop guy said its bad for a motor to not have 5500 rpms at top end. i want a second (or third) opinion from you guys. dont want to damage a new motor but hate to lose 7 mph at cruise. any thoughts on this are appreciated.