I also am thinking of caving in for MCU2 due to the 3G planned obsolescence in February.. Could just get the LTE radio installed instead, but at that point, the MCU upgrade gives so much more (aside from losing AM/FM radio)
Just got the upgrade yesterday haven't had much time to play with it only the drive home. My initial impressions are pretty much where I was before. It's nice to have the additional speed the operation is more seamless. And for those that would make use of it the web browser now works as good as any. (I will likely use the browser on occasion now that it works it is a more comfortable and larger screen to look at for checking email etc. while sitting at a supercharger) And there is a path forward to keep your radios for an additional $500 I kept FM and XM, AM radio however is lost.
If one is not a serious gamer and is not that interested in watching movies and videos and so forth in the car then the cost / benefit didn't add up in my case. I wouldn't have done it if I didn't have other reasons to do so which is probably where you're at now seeing how 3G is going to sunset.
My local service center discounted my upgrade by $250 which is the current cost of the LTE upgrade which I had previously paid $500 for.
If your MCU is working and you have no other issues with it for $250 the LTE upgrade might be a good option.
A final note the resolution of the images rendered in the instrument cluster is much better, it is now equal to that of the center screen if that is of any value.