My knowledge of Stingrays is minimal, but..... Design wise they haven't changed at all. Materials have changed a bit, for example, up until the early nineties they used birdseye maple for the necks,and the body woods may have changed(?). Neck profiles have changed since the pre Ernie days. My '79 neck was quite wide, but shallow depth wise. My present '98 has a slightly chunkier neck which feels like a 70's precision to me.
Electronics wise, some people prefer the 2 band eq over the three band. There are some threads mentioning it on here. There is also the "weak G string" which some people have brought up. Not noticed it myself.
Can't think of anything else.
If you're looking for a slimmer neck/more versatile sounds, have a look at the Sterlings. Also there's a new range of far east models such as the Ray 34, which are getting good reviews, and come in considerably cheaper than the US built ones.
Hope it helps a bit, Nige