I have been using white sailfin mollies as dithers with my GT and JD for a few months now with no issues at all I really like the look against the black background. The fry don't last very long but that was the whole idea so it worked out for me.
Plants IDK hit or miss there see what happens tugging on the fake plants may = munching on the live ones.
The MTS is a great idea with the loaches. Hope they don't do such a good job they can't establish. I had a good population in with my Discus untill I added Dwarf Loaches and in three months they were all gone.
I think it's a good plan. Better than my foray into Tiger Barbs....lol