Fred, IMHO any 10' 8wt is a tad bit overkill for still water, unless the fish involved are 5lbs and up. I wish I knew more of those places!
If you like the GLX 6 wt, I think you might really like the XP. They have a similar, super light, crisp feel. But it is tough to say. The TLS 5 wt is similar in action to the SLT, but comparing a 8'6'' 5 to a 10' 8 isn't really valid.