I can only tell you based on buying two Williams diesels with True Blast Plus.
The bell and whistle sounds are loud and strong.
But, the one with a single can motor starts out strong pulling a medium train, and then in about 2 minutes starts to fade, until it slows down to half the original speed. Not good.
The one with two can motors is great.
So, as to the steamer question, I wouldn't buy a steamer with a single can motor in it, except maybe something like a tiny docksider engine.
Hope this helps.
Mannyrock