Viktor, yes, I am having and using the X3. Came from N95, 8GB, N97, E7, E6, Lumia 800, 920, 1520, 950XL, HP Elite X3. Know ipads and iphones pretty well due to professional responsibilities, had iphones, have ipads. Not as good as a support agent, but I know it. I am a Security Manager, doing processes and audits, also a network, firewall and MDM guy, getting his hands bloody in medium environments.
Windows 10 mobile: Yes, there is a filesystem and you could swap files using a cable and USB Stick, e.g. just connect it and copy stuff from and to. But really, the guys here are all giving great advise. Ask specific questions and we will give our best to help you optimise it.
Like I said, personally I would rather optimise my usage of the 7+. Or just try, if money is of no concern. Get one in parallel and see, how it works. Stay away from insider builds, dont ask, if you dont know ☺
I would not touch a pixel. Personal and professional opinion.
Best regards,
Corwin