I have an XPS 13 9350 running Ubuntu 16.04 (touchscreen).
Is it OK to update to Ubuntu 16.10? And then 17.04?
(unofficial support) yes, but as with any update, make sure you back up and expect things to go wrong. If you can wait a little bit, I would personally recommend waiting until two weeks (kinda arbitrary number) after 17.04 is released. In other words, wait one more month. Then, I would personally recommend a fresh install instead of an update. Or, do an update and if anything gets broken then do a fresh install. Currently I'm on a 9343 DE working on a fresh install of 16.04. But since Dell upstreams fixes, I think that a fresh install of 17.04 will perform very well for you.
Thanks for the advice. I'll wait and then do a fresh install.