Well, I'm another 2S to 4S convert- who converted back to a 2S. I quit riding bikes about 12yrs. ago and had always had 2S, well, about 3yrs. ago I got bit by the dirt bike bug again. I read all the magazines(I know, big mistake, but the mags were pretty decent back in the 70's/80's) and BB's and researched everything I could find on the 4S, and everyone seemed to think that they were the end all, be all of motorcycles. So I took my hard earned cash down to the Yamaha dealership and plunked it down on a YZ426.
The bike gave me reliable service for 2yrs, and I hated every minute of it. So I saved up some money, FINALLY traded in the 426( tried to sell it first, no takers- and it was in perfect condition), and bought myself a 2S. Now that's livin'.
Yeah, the media tried to sucker me in to another 4S. They've got less compression braking now they said- Yeah but they've still got more than a 2S. They're lighter now they said- Yeah but they're still heavier than a 2S. They handle better now they said- Yeah but they still won't turn inside of a 2S. They need less maintenance they said- Yeah they MAY need a little less maintenance, but it's twice as complicated and takes three times as long as on a 2S.
Now, having said all that, I know several people who have went from a 2S to a 4S and are very happy. And, as evidenced by this thread, there are other people like me too. If you can, ride a 4S and see if you like it better, and if you do, buy it. But don't be surprised if you still prefer the "outdated" 2stroke.