I haven’t tried the XS on a 12 string, but I have tried a set on a Sexauer guitar I have – and they aren’t bad at all. I can’t speak to their longevity, since I know that my SCGC strings give me great service life, but the have good tone so far. The set I got at a local shop cost me near as much as a set of SCGC, so unless they come down in price, I’m not inclined to pursue them further – but until the SCGC 12 string set comes along, the XS or maybe the Nanowebs might be good options –
I have a 12 string XS set I ordered but haven’t installed yet – maybe this weekend I’ll take the time to do that –