Karlis: I own three Yanagisawa sopranos . . . S992 (like the S991 but made of bronze), an SC902 (curved in bronze), and an S901 (lacquered brass). They are so similar that I'd be hard-pressed to write anything about how they differ. I've also owned an SC901 (lacquered brass version of the curved bronze) and earlier models of their straight sopranos. If you've had a chance to play both, then you can answer your own question. But if you are buying sight unseen, then I'd go for the least expensive. One thing though - the S991 should have two necks, so if you prefer the curved neck, that makes your decision. But if you like straight necks on straight sopranos (like I do), the choice is too difficult to define. DAVE