A cautionary word for anyone fitting a DCC decoder to their 9F; take great care not to dislodge either of the copper coils on the PCB next to the DCC socket. I don't know how I did it, but one of them came loose at one end so that the motor would not turn until I had reconnected it. I managed this by unwinding a coil and soldering the newly freed end to the pad where the original connection had been made.
I used a Zimo MX 63R decoder which fits in the boiler space provided quite easily. The MX 63R is smaller than a Lenz Gold, though I don't the installation is any neater than Doug's in his 9F review. The difficult part is constraining all the wires in the harness until the body is mated with the chassis.
Hauling power appears to be well above average. The 9F has few problems with a CMX clean machine on the level, but there can be wheel slip when pushing it backwards up a 1:25 incline.
I have fitted a pair of Kadee long length NEM couplings front and rear with a sliver of 10 thou plasticard to take up the "slop" in the factory fitted box. It looks like shorter NEM Kadees would work, but for now I am content with the long ones. Being an NEM fitment, changing at a later date should be no problem. I fitted the front Kadee whilst I had the front pony truck removed when adding the DCC decoder.
Mechanically my model appears perfectly sound with no evidence of the "rock and roll" that Doug has commented on in his example.
All in all, a most satisfying model; highly recommended.