It works like a charm for one shopper group.
It has great integration to joomla user group.
There is a bug in virtuemart integration for multiple shopper groups.
There is another bug - changing subscription level doesn't work you have to open a new subscription and delete the old one.
Thank you for your review.
The two reported bugs are actually not bugs.
The VM integration only supports assigning one shopper group per user. When we were building the integration plugin –about a year ago– VM itself didn't support anything different (it was one shopping group per user). If you are certain this is no longer the case, you are welcome to tell us so. To the best of our knowledge this situation hasn't changed.
Changing a subscription level is not possible for the end user (subscriber) but this is a feature, not a bug. Honestly! Each subscription level can have a different length and a different price. Reconciling this is a daunting task and usually requires the intervention of a sentient agent, i.e. a human, who can understand how to best handle each individual case based on business policy and special considerations. Alternatively you can use Upgrade Rules which are designed to handle this issue exactly by providing automatic discounts to people wishing to upgrade their subscriptions. Of course the old subscription remains. A more elegant approach might be added in the future but I'm sure most people will consider it a bug as it's nigh impossible catering for all ad hoc business models.
That said, changing the subscription level from the back-end of the component is perfectly possible. We have to do it on our site all the time when people buy the wrong kind of subscription and ask us to help them with their wrong order.