I suggest to exclude moving of tickets between products feature from BEP-0010 and implement it as another BEP later. IMO, this adds additional complexity to already complex problem of product-scoped ticket numbering. We have to make sure that it will possible to implement later (e.g. by introducing of additional history table) but don't need to cover this in BEP-0010. I would concentrate on upgrade and import functionality as part of feature list we want to have in 1.0 release.
I think that changing of tickets primary key to something like id+produc_prefix (Alternative 2 in BPE-0010) is the best solution that provides plugins backward compatibility and product-scoped numbering as users would expect based on experience from Jira or Redmine. We already have DB translator that emulates product scope in DB for legacy API, so it should not be a huge change to simulate auto-increment behaviour also. Cheers, Andrej
