The Ion is shit in every way except its internal operation.
1) You have to completely take apart the marker (body off frame, unscrew the body in half) in order to do regular maintenance and to clean out a chop.
2) It has a trash feedneck that won't fit most loaders
3) It has a dogshit board
4) It has a dogshit trigger
5) It has dogshit ergonomics
Basically, you can make an Ion great, but you won't be using any of the original parts. Most important is an Xe body, or other BoB style (Lucky 5.1s are the best IMO) Without that and the rest, it's a headache to own on the field. Yes people can manage, but it's not worth it. How do I know? I own 2 ions myself.
That's also why the Dye Ion and GoG Ion (the Proto Rail and GoG eXTCy) are so much better. They work the same (which was never a bad thing), but already have these exterior problems fixed. They come with good boards, clamping feednecks, etc. (except Proto Rails before '09 had shit triggers and feednecks that broke when over-tightened)