It would be very helpful if the base code was public on Github or Bitbucket.
There have been minor improvements that I've wanted to push back to you guys, but sending patches takes so much time. It would also make upgrading easy.
As a company, your software would have some more exposure, get really good issue tracking built in, etc.
The only difficult part might be upgrading to pro using this system, but that could be handled with a local PEAR package applied on top of the Github base.