I'm not a big fan of the Demolisher as the launcher makes it pretty front heavy. The Rapidstrike really isn't very rapid at all without upgraded batteries. I think people who use Massdrop would want to go for a Rival blaster so I'd recommend either the Zeus or the Apollo but I also really like my Hammershot so that would also be an excellent choice.
AnAbstruseOrangeBearYeah, you have to mod the rapidstrike and rewire the motors (or get better ones) and then use higher voltage batteries to give it a good firerate, otherwise semi-auto is actually faster.