Hello Ed:
I have not cast the rod with any of the Windcutters, and the XLT 6/7 is quite a bit too heavy for the rod if you have more than 70 feet of line out. Cutting back the fat part of an existing 6/7 XLT by 20 feet gives you a line with a belly length of about 65 feet, and this works well as a stop gap. I am designing a 6 weight XLT2 which is bang-on the new spey standards and which really casts well with the LS2 1206. I have cast an SA XXD 8 weight single hander line with this rod and it works out well (Spey lines cast about two to two and a half line weights heavier than AFTMA single hand line standards, in general). Jerry Siem has a line for his 5 weight spey rod, which I have not cast on the LS2.
I hope to have the new XLT2 lines finalized in the next month or so, and also hope that SA will release them for Board members to try out.