(I have a bad case of the Flying Butt Syndrome which is due to me bringing my lower hand way the Hell out there on a two-handed cast).
Thanks for posting this. I don't feel quite so ashamed now. I thought I was the only one on this esteemed board with experienced spey casters who suffered from this malady. I previously could only admit it to myself, or those who saw me on the river.
There is hope for us, I think. My last trip I actually got in a groove on a classic cast, step, cast, step run, where I could think and work on both of my 2 major casting problems simultaneously. (Usually I'm fishing small holes, or spots with only a couple casting stations, and can never get into a good rythm.)
I, too, find my single-hand spey casting much more consistent than my 2-handed, and I love it for trout fishing. I use a DT on all my single-hand rods. Since the front tapers on standard WF and DT are typically the same, I generally don't see an advantage to WF, either, and the ability to flip ends of a DT as it starts to wear is a big advantage for people like myself who are pinching
pennies to help pay for my kids' equipment, among other things. (My 12-yr-old daughter has a pretty nice double-spey with a 10.5 foot 9 wt. 2 hander!) I believe a line with a longer front taper (such as a TT) would be better for single-hand spey casting, but I haven't tried it.