I agree with all the posters that say it's not all that important which grease you use as long as you use enough of it to begin with. For over 50 years I have been looking at tests and mechanics advice and wild claims by mfrs. and have never been able to determine that one grease is noticeably better than another for bike use. Any of the bike greases I've used have been fine but so have the cheap tubs of marine grease I bought at the auto parts stores. If you feel better about buying the overpriced bike specific stuff go ahead as the cost of using a small amount every year is pretty minimal unless you're doing a fleet of bikes. For a good article explaining greases checkout forum member
BikeGremlin's site. Of course there will be detractors from his advice (true of anything having to do with lube discussions) but from my experience he is right on.
The best bicycle bearing grease | BikeGremlin