Hi,
I got 2/3rds the way thru my build of the Dusseldorf and had to stop due to ill health.
I have based mine on the early short version shown on this site -
http://www.flb2.de/
I have made the superstructure a lot more scale like plus moved the rear monitor back to the correct position and also the crane on the back to the correct position where it loads/unloads over the stern of the boat. The problem was with the rudders supplied were fouling the operation of the crane so I fitted scale twin becker rudders (machined down Billings Smit Nederland ones), and now all works well. I wouldn't recommend the motor/ gearbox setup that they suggest, you will hear them screaming from fifty yards away. I fitted direct drive on mine. If you do the deck as suggested it looks appalling, I have used Slaters plasticard chequerplate for mine and is the correct scale appearance.
There is a German site dedicated to the building of these models, and is part of the above site -
http://flb2.muelhoefer.info/
The 'kurz' is the short version and 'lange' is the later modified longer ship.
There is a chap on there that has built the long version and has designed a superb operating anchor winch, I built one from his instructions and it works great, it will 'drop' the anchor and when retrieving will auto stop ready to drop again when needed. This could be used on other boats if you use one of the F series sets or switcher modules. His site with vids plus other info is here -
http://www.dahmen.de/
It took a lot of working out, you do not need the twin stick radio (I took the twin stick out of mine and reverted back to single stick), if you fit the scale bow thruster as I have, and also I have managed to get everything working at the scale speeds (slow rotation and elevation of monitors and the rear crane). Everything can be done with the F14 transmitter if it is fitted with the two slide switches in the central positions with the multi switch prop 12+2. The total cost of the electronics for this boat including speed controllers for main motors and bow thruster, engine sound board, siren, working radar etc, plus all the small geared motors and the controllers for them will come to about £600. So with everything thrown in it will eventually cost about £1000. So when you see this kit advertised for around £150 it is only the basic model, everything else is extra.
John