I’ve found https://tedgustaf.com/blog/2014/fallback-property-values-in-episerver-using-attributes/ a very useful thing in CMS 9-10 and can’t imagine a life without it — I started using it in CMS 11, but got strange behaviours where blocks appears or disappears after one compile (or IIS-reset), this is mentioned in forum posts.

My latest comment in that issue: https://world.episerver.com/forum/developer-forum/-Episerver-75-CMS/Thread-Container/2018/2/weird-issue-with-items-dissapearing-from-contentreferencelist/#199538

I would really like to use this in CMS 11.

So I think this would be a candidate to be included in one official Nuget package so there will be a supported version whatever changes you do to ContentDataInterceptor, that nowadays breaks basic functionality if extended (even with just base.method-calls in overridden methods)