Just as a suggestion when looking for additional beta testers.
Only a handful of people really use the subscription feature. I think one of them should be enlisted.
It is extremely difficult to test that feature unless you are actually using it.

keep in mind that the paypal sandbox is a place where you can simulate payments, subscriptions, cancellations etc etc.. all for free..

so technically you don't need to have it 'live' on a site to test it with fake moohlah

I was not aware of the "Paypal Sandbox".
Is that like a kitty litter box? LOL
But I still think someone with a genuine interest in it working would be the best to enlist.
I see posts here that very few people can answer because they don't use the feature. Such as myself.