I have been using ente.io for few months now. It does what i want, to back up my photos. AI and all is something i personally don't care much about. But i would love to have location clustering.
It is often better to get feedback while the user is using the product that is what we recommend at http://featuremonkey.com/
When you send an email and ask user to give feedback they don't really have an incentive to give feedback, maybe giving Amazon gift cards etc.. can increase the likely hood of reply.
The placement of give feedback link can be really important.
Maybe keep in near places where you are more likely to have issues or you want feedback from.
A lot of the limited ones which exists are for high volume transactions, so it matters a lot more than we think. But the hype is sometime way too much.
Pretty happy with it.