Im really happy with my Gen 1, thats why I decided to keep it. They said they would ship me a gen2 complete upper for free but I would have to send them my Gun 1. Not keep both.
They also said that the new caliber conversions coming (who knows) will only be compatible with the newest gen, but if you're a gen 1 owner, you get the whole new upper with conversion for the same price as the new barrel, so in that situation you would get to keep both your existing and get a whole new upper and barrel for only the price of a new barrel. Seems like the best deal to me. But honestly who knows what will ever be available, and 9mm is fine. I don't feel the need for any other caliber anyway, its just a fun gun for me, its quiet, short/maneuverable, and good for hunting rabbits/varmints. My view is ill just have fun with this for a few more years and then probably buy something else thats the "coolest" at that time.
I think Sig has done a lot for the firearm industry, so I try and stay positive. I know they have their issues, but I went into the MPX knowing the caliber conversion advertising was probably not going to happen. Sig definitely likes their hype, but if you read into the reality and know what to expect, I think Sig is pretty awesome. The MPX is great, I try and love my MP5s but they just cant compete with the MPX when it comes to actual use. Plus more innovation and companies the better, HK and Colt had a good ride, but they better start catching up.