re: Next Wave CNC Shark and Other Models

This is the type of review I really like, details and opinion on whats what.👍

I really don't like proprietary stuff. It's "ok" when it is for some special function not offered on other machines and is actually useful (worth the extra cash), but as you say, they can really go too far and limit the potential.
Good for "turnkey" where you just want to make something, but horrible for evolution.

I keep eyeballing these type machines and certainly the Sharks are heavily advertised,   but now I'm a lot better informed (big thanks!)

Personally I'd love to find a mechanical unit like that for cheap and just strip away all the voodoo and install a more generic controller. These have become very common and even more modular with interchangeable  motor drivers so 
upgrades are simply a matter of swapping in a higher current driver for any bigger motors or items like your new spindle.
Once you have a G-code frontend with all the tunables available in the driver, I think the options for producing stuff is 
unlimited with the rapidly evolving world of development software tools.