Final Decision: JAMES VS JAMES

I'm a big fan of the tender-battery engines, in my Gordon I cut out enough of the tender to fit x2 AA batteries in (but I'm pretty sure that you can fit in x2AAA batteries without much effort) that means if you want to do a 3v conversion it's a lot more feasible. Also the engines with the combined battery/drive are usually flat drive transmissions, they are fine but when your upping the power there isn't much room for additional ballast. when I did my Spencer mod I had to move the battery pack into the tender which wasnt ideal as the coupling is the disconnect type rather than the fixed loop to loop,
Not only that, but because I had moved the battery I had to ballast the engine to keep it on the tracks, and the only real place to add additional weight is in the battery oriface



So for me I would always go for the tender with the battery in (even if the wires can fail)