Nice work dude! Glad my lucky IMX is taking good care of you
Looks like the river has given you a nice send-off to your new life as a married man.
You know my opinion on all this DT stuff. I'm no expert just an average hack who has been thru the wringer.
IMHO if you can keep the d-loop up&out on a DTF and stroke in-line against a lightly placed grip it's going to fly nicely, and these principles apply to all other lines except for short heads. There is a trick to keeping the loop up to get the most out of that d-loop into the rod for the casting stroke with a DT and it's very much worth learning.
FWIW - It's not necessarily bad to have the butt hand up, but if it comes up your other rod hand must also come up to maintain the angle up to the 1-2 o'clock firing position. If the rod dips down in the back as a result of raising the butt hand, then the d-loop will fall into the water and you will have to lift a wet mattress to make the cast.
In fact while watching the d loop one might tend to raise the rod at the end of the kick as you time the landing of the grip. The better your set, the less you have to raise to compensate. Coming downward and forward with the casting stroke (if I am not mistaken) is common technique of the underhand cast and seems to add a little power to the stroke. So it's more a matter of rod position and load from the d-loop than butt hand position IMHO (others please correct if I am wrong).
A dense head (like yours truly

:chuckle: ) lets you get away with things that you can't do with long spey lines, particularly the formation of the D-loop. You can pull that head behind you any way you want and still load the rod for a tip cast. You can stop, check your watch, pick your nose while the head sits there in the ready and still complete the cast . Not so with anything longer than 40, 60, 70 feet or more.
But what do I know - my learning was put on hold for the last 7 years - I've only Spey cast once a year. I just wasn't getting the time in, and was stuck in head chucking mode. But this year, thanks to the inspiration from the Spey Clave, I've dedicated many fishing days to Spey casting with a puff of yarn 3,000 miles from my old home rivers. After getting some advice from Simon Gawesworth at the Sandy Clave, and spending many hours casting I recently debugged a component of my cast that was nothing short of a revelation.
Excuse the giddy ramble, but it was when I went back to those DT principles and spent days just casting (and not fishing) I finally got over a major hump and can produce a consistent D-loop, small grip, and tight effortless loop on a change-of-direction cast.
It's been a relief and I am totally psyched to cast more rods and lines - when is the neXt sPeY cLaVe i NeEd a fIx bAdlY!! :chuckle: