First post here so please be gentle!
I have a number of old Decaperms that have been taken out of models in favour of other motors, you can get Decaperms to run in very smoothly with little noise, just add PTFE grease to the gearboxes and run them on load for about 5 hours, current draw drops to... But I now take standard 550 motors and rewind them for the performace I need.
I have the same type of motor turning 30mm semi fast props upto 70mm direct in tugs, its just the wire size and turns that change the motor state of tune.
If anyone wants to try this, just stip down an old 540, remove the wire and rewind it wtih .31mm winding wire 80-90 turns per pole... should give you v high torque, and around 4k rpm.
Hope this helps..