I would rather save a little more money and go for broke on a PCM Big Boy. So much more loco in every way in my opinion.
Hey, even the Trix one is in some ways better than Athearns Big Boy.
I wouldn't walk across the street if they were giving away Trix's Big Boy. What a piece of sh........overrated engine!!! For the price I was expecting a live HO scale crew to be on board. The magazines hyped it so much pre-release that it was a disappointment when it was finally released. Detail is nice but down on power. I came awfully close to buying one. Got my Allegheny instead.
I have yet to see a model, other than brass, out can perform Rivarossi's Red Box offering for shear pulling power. I've got a Mallet (a 2-8-8-2 equipped with traction tires on eight drivers) that has pulled 239 coal cars at a show in Fort Wayne, Indiana. We ran out of coal cars or the number could have been higher.
I have both of my RRB Mallets converted to DCC. Pretty straight forward conversion. I you intend to run it "heavy", with long consists, you may want to step the chip up in amperage as I did after frying a couple.
The decoder in my steam engines get plenty hot. I epoxied them to the cab floor to prevent a lot of heat build up in the boiler, and provide a bit more ventilation to cool them. Though there is plenty of room in the boilers to place them if you think heat won't be a problem. That is your decision. A couple of toothpicks through the cab windows will hold the decoder until the epoxy sets up.
I placed the speakers in the tenders(down firing with slots cut into the bottoms of the tenders) and ran a jumper, with a plug to disconnect the units for storage and transport, from the engine to the tenders.
I have a pair of older AHM/Rivarossi Mallets(motor in cab) that I haven't tried to convert. Keeping them for parts, just in case.
Even my C&O 2-6-6-2 Allegheny(love those "flying" pumps and all of the hardware on the front of that thing) is a beast, having pulled 150 coal cars during an operating session on my layout with a 1.4% grade, or there about.
Mike, I have a old remotored Tenshodo Big Boy. Yes, they are beasts!!!! As you say, quite noisy. No, not just quite noisy, VERY noisy!!! Even more so than my Centipedes and those are NOISY!!!!
Bob