As you know, Lee, I opted for the TK60 in my Cromwell build. It's certainly more of a challenge fitting it in, given its size, but as you can see from this pic, it does go in neatly in transverse orientation (like a Mini engine). I opted for this unit because of its future potential, robustness (drive train amperage..), and also because of those amazing Rolls-Royce Meteor Cromwell sounds from Stian.
I use it with my Spektrum Dx6i.

- Cromwell with Clark Tk60 electronic heart
Using a 10-channel TX would confer other benefits, as channel sharing can be a pain; but I just happen to like my Spektrum radio..

Incidentally, I had to revise the turret layout slightly after this pic, in order to make more room for the smoker pipes.
"Get your facts first, and then you can distort them as much as you please"- Mark Twain.