Hey at this point in my life, I just buy the new books as they come out and don't much care about the small details. Now I will say this I have played and collected D&D my total time that I have gamed some 37+ years, BUT stopped buying anything for D&D version 4.0. I will say I still buy a lot for Pathfinder 3.5 or 3.75 still but refuse to buy the D&D 4.0 stuff. I might look at 5.0 when that comes out, but even then I might not bother with that.
Now if you have the Traveller books of the past, well you really don't need the re-imaged Mongoose stuff but I would buy it anyway just to have it incase there is some new item that is added. Plus I like to show my game support for my hobby and the cost of anything is really not going to break any ones piggy bank.
Stuff is nice. I like stuff too, but I'm afraid I've reached a point in my life when I can no longer acquire stuff for stuff's sake. Physically I don't have any more room for stuff, financially I can't justify spending £20-£30 for something I'll flick through for ten minutes and then set up on my already overburdened shelves (or screaming hard drive). I like to support my hobby too, but my hobby is not exclusively Traveller and though the cost of anything may not break any ones piggy bank, the cost of everything would kill mine.