I have almost completely migrated to PF powered models, but still build som "old" 9Volt powered models.
When building small shunter yard locomotives, it certainly helps to only have a 9V motor, and to be able to focus on detailing more than hiding bulky PF components.
My design is partly based on E69:s built by PolLUG and LatLUG.
Base is 7wide with 6wide hoods and 6 2/3 studs cabin, and overall length just 16studs (buffers not counted).
With extensive use of SNOT and various offsets, I think the look is quite prototypical.
Feel free to comment. (if I manage to upload photos.....)