Well--the problem w/ the strats is the bridge. I have a Peavey Strat-like anomoly w/ floating tremelo, twenty four frets and a 25 1/2 inch scale length. I put five springs in the sucker, put some Beefy Slinkies on it and I'm good to go detuned to B. It plays great and stays in tune except for when I use the wang bar.
The SG intonates pretty alright but it would be nice if you could get the saddles another sixteenth inch back on some stings. I pretty much have mine set for the longest string length possilbe. It's very playable. I used it detuned to B for years as my main guitar, recorded w/ it, etc. all w/ no problems. I didn't even have to adjust the truss rod on it--actually, normally I don't. I do have trouble keeping the third highest string in tune though--but that happened even in standard.