I do a lot of winter fishing for trouts and after all, I went away from sinking lines. Because they were not available in trout Spey spectrum, I was experimenting years.
After all, I would assume, you won’t get the expected benefit in numbers of catches using sinking lines for trouts. I am talking about river fishing.
I for myself go that far to use a Scandi floating Belly with an Intermediate tip for trouts most of the time now, adapted with a long tapered leader, seldom a Polyleader and even more seldom a Skagit and heavy sinktips. The latter only for the heaviest and biggest flies in windy conditions in spring.
-Grace of Scandi, grace of tapered long leader spooks less trouts. They are mostly more „educated“ than our beloved searunning species, especially in c&r water or places with high fishing pressure.
-Adapting depth with weight of the fly on a long Mono leader after an Intermediate tip is not that much less effective in achieving depth, compared to unweighted/weighted flies on a sinking line, heavier sinktips or sinking Polyleader with too short tippets.
-It’s astonishing, what size and weight of flies can be turned over with a Scandi, well adapted in rod and line pairing and how quick a change to a soft hackle is done.
-Trouts want/need speed, also in winter, especially the experienced and bigger ones. Much better versatility, to speed up with a floating line/floating Belly or to do the opposite, to slow down and let the fly go down on a long Mono leader, then quick change again, depending on situation and tactics.
-We can use „fishy“ Spey rod actions with more feel in the Trout Spey game, where possible.
-More fun in casting and fishing compared to a „cast the sinker and let it to itself“.
My biggest trouts in winter:
Caught in flat and fast water near the bank on a high speed fly in a retrieve, fishing for Danube Salmon (hucho hucho). Trouts in sizes that were thought to be in the deepest pools...
But maybe your trouts are different and I would do it totally wrong over there...
Time is running... A little bit of work, a little bit married, fishing, hunting... What else?