Got mine today, finally. Unbelievable detail, the pictures don't do it justice. I haven't had a chance to check pulling strength but I don't expect it to be outstanding. It seems like it could be heavier. The engine runs silky smooth, incredibly low starting speed. Quiet as can be.
The only thing at all I was disapointed in was the tender pickups. The rear truck on the tender is wired, both rails, but the front truck, even though it is the same style doesn't have the pickups included. It looks like all it would take is the two metal pickup strips applied, a shame they just didn't include them to begin with.
After I get a chance to break in the Berkshire I will have a better idea what it can really pull. The break in track has been busy with a ConCor/Rivarossi 2-8-8-2 that I picked up last week. It is a first run loco that was new old stock from a hobby shop. It has taken a bit of work and runtime to get the 30 year old dried up grease out of it. About 3 hours of break in, it has started smoothing out.