The mpsGeneric flag complicates persistent-template considerably and has a dubious value proposition - it allows you to reuse a model in a SQL context and a Redis context and a MongoDB context.

This doesn't seem very useful. Removing it would be great. But I don't want to break people who need this for some reason.

Unfortunately, I can't just, like, collect data on this. What I can do, however, is deprecate the field, and link to this issue. Folks that upgrade will see the deprecation notice and be able to common on whether they use it or not.