Give this one a try: http://forum.xda-developers.com/showthread.php?t=1363593
I think you'll find it icy-sweet enough
True, Samsung doesn't care about software updates, but that doesn't mean you shouldn't either.
Oh, and if your GPS antenna is broken or has bad contacts; you can order a new one for roughly 10-20$ off eBay, replacement is easy with just 2 screws.
However I usually find external bluetooth receivers with SIRF3-chips the best; my "Road66"-one even manages to get a steady and accuracte fix in large cities, has 6 hours battery charge and takes around 10 seconds to cold-start (I dont know how it does it... amazing!)
I for one am quite pleased with my Galaxy S (first revision), even if not with Samsun'g customer service. Well, that's what homebrew is for, isn't it?