I know we discussed Euan Gamble but I thought I would add it here in case any of the other beta participants had any strong feelings on this. So at this point in time we do not let our business users use Nintex Forms as we think without training it can be quite dangerous and cause us a massive support workload (there are other non-Nintex tools that we lock down similarly). To that end we have a custom solution on our environments that hides the Nintex Forms button from anyone who is not in the Site Collection Administrators group for the site.
When responsive forms drops I understand that we can choose between classic and responsive forms designer for list and task forms. I would like to be able to easily manage the governance on these (like we do for Nintex workflow).
So in an ideal world what I would like is:

Pixel Perfect – allowed forms designers
Responsive – allowed forms designers
Is that an option?
As responsive forms is so much easier to use I would be happy to let our users have access to that designer as an option for them.