Sure, off the top of my head:
- Redundant functionalities / features
- Pay options or features linked to payments should ideally be moved to pay plugin
- Users can delete accounts when the option is unchecked
- Reset settings resets all of the plugins settings instead of just the section being viewed
- I recall seeing an error with the mobile phone field when selecting it view BO and other plugins that can activate/deactivate the same field
- User type select is added to forms without a heading/title for the field ie. Account type:
- Outdated layout in comparison to other plugins
- Operational/management views should be separated from configuration / administration views as you currently have to dig for them. To be honest, I think this should apply to all plugins.
- Some forums users have either proposed or coded some nice features that extend search, layout of results, and other functionalities - instead of missing out on them (as searching for these contributions on the forums is cumbersome), why not consider adding them to BO?
Point being, whenever something breaks after an update (plugin or core), first thing I do is disable BO prior to debugging. DOn't get me wrong, it's a very useful plugin and I'm glad I bought it, it just needs to keep up with core/other plugin updates.