Fleischmann is an old-school company, so they use old-school technology (motors). They might be old, but they run fairly well. Sometimes when Fleischmann redesigns a chassis for a loco, they use more modern motors, but most are still old school open-frame motors.
If you want a small decoder with 8 functions which also has the 6-pin interface, I would forget about it.
Even the ESU LokPilot nano decoder doesn't have 8 power function outputs (some of the functions are logic only). I think some of their larger scale decoders have 10 (or 12 if headlights are counted) power outputs, but all the smaller decoders have fewer than 6 (and some are logic level outputs). Same with Zimo decoders. I haven't looked at Digitrax, TCS, NCE or Soundtraxx. Maybe you can shoehorn one of the larger scale decoder into this wide body model.
You didn't mention sound, so I assume it is silent decoder. One thing that might work is to install a standard NEM651 decoder (like LokPilot micro) in the socket, then also wire in a LokPilotFX micro for the additional functions (since ESU decoders can map any function to any outputs). These are small decoders (8.0 x 7.0 x 2.9mm)