[rdonj]

Gundabad warriors are about half the resources for a unit with more defense, more or less the same prot, more or less the same morale (due to berserk), and 2 less hp... other stats are a bit worse off, and they only have mapmove 1 instead of 2, but if I want a higher resource unit I'd generally prefer the warg riders to the elite warriors because they fatigue out less quickly.

Barrow wights aren't a good deal JUST for the research, no. You'd be better of making skull mentors if that's all you want. But there's no reason to make skull mentors because they can research, fight, forge, search for magic sites, etc as needed. They are much more versatile for basically the same cost. And they'll never get useless like skull mentors eventually will. You still want to forge lightless lanterns though. Also it's not strictly necessary to summon them with the witch king until you get the proper random if you use a skull staff, which you will want anyway eventually. The witch king can probably spare the time to summon a few though, it's certainly a better use of his time than casting arcane probing or researching. Probably making them worse at researching or unable to reanimate (not sure that's possible) would be the best "fix", but I'd rather hear back from other people first.