I have been around a little bit before posting and now I want your thoughts about this scenario:
I registered a dozen of domains, all of them with the same name but different extensions for a project already halted.
All domains have traffic and pagerank, exchanging visitors among them, and all of them are established names for some years to simply drop them out or let them expire.
My question is, should I leave each domain as single underdeveloped websites, or should I redirect all of them to that with the highest rank which, btw, will be the only left with auto-update features.
Your input will be much appreciated :)
Short answer: There is no right, one size fits all answer.
Other answer: Per a certain Google employee a permanent (301) redirect is reportedly a "safe" or "advisable" approach.
Once you get down to the building of smaller sites you face all the usual issues: Sandbox, Trustbox, interlinking issues, duplicate content issues, etc.
My personal POV: If you have the resources to make each domain/website a valuable resource to/for a visitor AND each website has legs to stand as an independent website (people interested in A are not interested in C) then there may be some advantages to not merging A and C.
Others favor putting all their eggs into one basket, that is, making one big honking website that addresses all related issues.