Hell, I used one tonight; we're doing In To The Woods, and I got shanghaied into playing the weird clarinet part which switches to A clarinet for no apparent reason (i.e., it doesn't use the extended range, and the key isn't that extreme).
I'm going to have to buy a double stand, since I gave my little folding pegs away to young clarinet players over the past fifteen years. (I did check the bore of the A horn for spiders before I started playing it.
I love Sondheim's stuff, but this one is for the garbage chute. If I wasn't being paid and paid well, I'd not do it.