I have only been in the hobby seven years, and only have the one Rivarossi their H-8 Allegheny from the Chesapeake & Ohio. I believe the one I purchased was from the second issue of that engine, the first coming some years earlier, maybe 8-10? Anyway, I ordered the sound version with EU LokSound decoder.
First, the model requires some details to be applied. Also, it comes with two cabs, one with an extended roof rearwards if you can close-couple due to really broad curves. In the case of your Big Boy, I don't know if it will be the same. However, I can tell you to be very careful handling the alternative cab. The plastic is very fragile, particularly the post into which the single screw must be driven. Go easy to make it fit into place, and don't force the screw if it doesn't line up. Ask me how I know this.
Secondly, the model looks wonderful...the H-8 that is. The detailing is second to none, rivalling even the P2K Heritage series steamers. The H-8 has white tire rims and the edgeds of the running boards around the boiler ar also white. I found the paint applied to the tire rims to be second rate in my instance. Perhaps other models were better.
Running quality, they are very good. My Allegheny is a powerful puller, although it comes equipped with traction tires. I don't feel they hurt anything running quality-wise. If they wear out, you can get better ones from third party sources. Many people elect to just tear off the traction tires and run the loco without them...they run fine.
I hope you get more specific guidance from someone who actually has the Big Boy.
