Hello,
Thanks for your post.
There is no “standard”. Many devices for making music (guitar pedals, synthesizers, samplers, etc) use all different kinds of power supplies. Eventide products are not the only stompboxes that use center positive power supples. Almost every power supply that can power multiple stompboxes has solutions for the different sizes and polarities that are offered among the different brands and styles of guitar effects.
Similarly, there is no standard for footswitch size. That is why Barefoot Buttons, for example, offers different sizes. You can use the Big Bore with the H90: https://barefootbuttons.com/sizing/
The H90 Control software can be change/updated, we are working on improvements for Program management and I believe that should resolve the issue you mentioned about accidentally deleting patches.
