I'm currently using the Rogue Spectra flemish 18 strand on 3 of my longbows. I like them. They're well built, the Halo serving is very nice, and I don't think they stretch much. After shooting them in, maybe 50 or so shots, I adjusted the brace height and haven't had to readjust since. I've had them on for about a year and they still look almost new. I shoot a lot, but I also take care of my strings, checking them regularly and waxing when needed. And I unstring my bows after every shooting session.
I would have no hesitation recommending these strings.