Tetsudou controller problems

My battery powered Tetsudou controller was delivered yesterday. I unpacked it excitedly, sat my Bachmann streetcar on the track and - nothing!! Well, the lights came on, but that was it. Tried posh Duracell batteries, still no result.

I then tried the batteries directly on the tram - still nothing, so I guess 4 AAs don't put out enough juice for the Bachmann motor. I found a 9v PP3 in the cupboard and connected it to the wheel - this resulted in a reasonable pace.

Since I really like the controller and being able to operate away from mains power, this leaves me two options. I could fit a PP3 into the device. It comes apart easily enough and there's more than enough room. My only concern is that there's a fair bit of circuitry at the top and I don't want to burn it out with a 50% voltage increase. Has anyone else run them successfully with an uprated supply?

The other alternative is to stick to models that work on 6v. I'm not particularly in love with the Bachmann - it was secondhand so I should be able to sell it on without loss, and I was going to order one of the TM-TR01 based models anyway, plus a Portram or two when the chasis comes back on sale. Being Tetsudou models, these must work with the original setup? If I take this route, am I painting myself into a corner regarding future acquisitions? In particular, I could be tempted by something from Modemo in the future.

Any advice would be welcomed!