There was no impact on the regular dart performance and now it shoots everything. Why not add this if you have a Nexus? It is very tight in my Nexus, but loose in my Aeon which was easily fixed with a layer of teflon tape.
Seriously all, if you have a pro blaster at all, do yourself a favor and get yourself this part. It works just as advertised and does indeed make any of your pro blasters into modular machines that will fire pretty much anything that can fit in a little rocket barrel. :) Even with the dead space and long barrel of a Nexus I was able to use this piece and the three dart inline clip for the little rocket to launch a Demolisher rocket around 20 feet straight on, and it would have gone further if I had more space to shoot in my range. To make a long story short. Buy the darn thing. Your pro blaster and the modularity of your loadouts will thank you.