I feel compelled to speak up
In defence of the XLT design. At the time of it's introduction, there existed among the spey community, a good deal of controversy regarding short belly (Windcutter) lines and the, shall we say, sloppy casting techniques one could get by with when casting them. Put on an XLT line and you discovered you were not the hot caster you thought you were.
Once you honed your casting techniques however, the XLT line allowed you to cast exreteme distances, mend pick up & recast, without the need for stripping. Not that the XLT was without it's draw backs. Like said, you needed ample room behind for your D-loop. Due to that long ,fine front taper, fly size & leader design, properly matched to line & rod was more critical than the shorter, lees refined front tapers of other lines. And then there was the wind.
There is a reason competition lines are always 10/12 wt lines. Wind! Competition casters were chopping the heaviest XLT lines, converting them to shooting heads, and they worked very well. But alas, the average spey caster was unwilling to devote the time & effort to master the technique of casting the XLT line.
And then there were the nymphers.
