I don't have a modern MBP (people say the 2015 models are the last best one?), but Office is pretty much the same (once you get into 365, then they are literally the same).
Dropbox works as you'd expect.
And Windows through dualboot works as you'd expect it to on an equivalent machine. With virtual machines, YMMV.
1 & 2 are non issues, I use both on my mac and work PC and they work flawlessly.
The obvious alternatives would be iWorks and iCloud, which I also love and use, obviously with less platform utility and iWorks really is not nearly as powerfull and feature rich as office, for everyday word and excel use iWorks is fine though.
3 I have no experience with, but from what I have heard it is not really a problem these days either.
Between your two options I would unquestionably go with the pro!
Thank you for your answers.
One more question : Touch Bar or not ?
I'm not the greatest fan of the Touch Bar but I have fiddled with for a couple minutes and the first Touch Bar config in 13" has 4 thunderbolt ports (vs 2), more storage and a faster processor for 200€ more than the previous one.