hey Matt, you should just get an 8" from Andrews (Google Andrews communications). theyre just as good and have more accesseries ane is cheaper for the gso counterpart.
with open clusters and globs you will see a lot more stars .. nebs will be brighter and planets will have higher contrast.
you will surely see Venus' phases and mercury's if you're lucky enough. Neptune and Uranus should be an easy find also.
you mention the Messiers, theyre all gettable with binoculars at a dark site .. so if you factor in aperature there's no reason why you won't be able to find them with an 8" in med lp.
good luck, I wish I started 18years ago ..
matt