What are the pros and cons of space marine allies/visa versa? It seems like Wolves and Marines currently compliment each other very well. Marines get better Predators, wolves get better Devestators. Wolves have better troops, but lose veteran capability if you take a full squad in a transport. Space Marines give great Unique models and are a cheaper way to get Divination as well as TH/SS Terminators, Space Wolves have better unique psyker abilities and cheaper normal terminators.
Am I missing anything? It seems like these two armies would synergize extremely well. (And I'm thinking 5 HQs per 2000 points... :D)
I think they do work well together but for different reasons.
Space Wolves despite getting a little dated still have some great cost effective scoring, long fangs still put out some great firepower at a great cost and Jaws is brutally effective against Tau and Necrons. What they really, really lack is air support/anti air which Marines can now provide thanks to the Storm Talon and Storm Raven and as you have said they also have cheap terminators.
I think the standard Grey Hunter/Long Fang/Rune Priest spam backed up by a couple of Marine flyers would work pretty nice.