Hi Niels
Welcome to this great forum where many are Märklin enthusiasts.

The little that I know is this:
ESU Lokpilot/Loksound 5 can have 2 inertia "registers" that can be used for a fully loaded train or a loco without wagons. For each you may specify different inertia paraters and install a function to select one or the other.

Märklin mMLD3 / mSD3 on the other hand have only one inertia register (Bremsverzögerung, Anfahrtverzögerung). The one thing you can do is assign one function key to ABV (Anfahrt Bremls Verzögerung). When activated this ABV reduces the time delay to almost nothing.

So the best decoder depends very much on the central unit you have CS3 or ECOS (CS3 in my case). this makes Märklin decoders very easy to use with a CS3 and ESU decoders very uneasy to use (Huge number of CVs and no user friendly interface). And probably vice versa.

Using Märklin decoders with a CS3 makes it very easy to control the parameters without having to reprogram the decoder
Just my opinion
Cheers
Jean
PS Your BR 24 patina is great. The loco is just great.
Your distribution gear on the video is not properly mounted (Breaking risk)
Here are my operations in my layout with the use of Rocrail
Using Rocrail or an equivalent would make it easy to switch from a fully loaded inertia to a single loco


Cheers
Jean