I have been required to upgrade or swap out sound cards on a several of my Conventional Classics. My 646 Hudson was unbearable. The bell and whistle sounds would randomly trigger non-stop. I removed the sound card and replaced it with an older generic steam card. My 2332 GG-1 also had one of the early sound cards which would constantly glitch, make strange sounds, or fail to trigger altogether. For this engine I purchased a GG-1 Railsounds Lite card during Lionel's 50% off sale. The horn and bell sounds are far better and I have the added benefit of electric "prime mover" type sounds.
I just don't see the benefit of installing TMCC or ERR components in these Conventional Classics from a cost standpoint. A typical F3 AA upgrade would involve an AC commander for the powered unit, Railsounds Commander, and some kind of mini commander for the non-powered unit. Don't forget you'll also be buying two coil couplers. You'll also probably want to remove that dumb on-board potentiometer from the Railsounds commander card and tack on some wires that run directly to the volume pot already provided on the engine. Otherwise, you'll be removing the shell every time you need to adjust max volume. You would be dumping nearly $300 into a set of engines which only costs about $200. And if you wanted to MU those Budd 3 car sets, you would be looking at 6 electrocouplers, an AC Commander, Railsounds commander, and 2 mini commanders. Of course this is usually where someone clever steps in to say how easy and cheap (but ugly) it would be to drill a bunch of holes, cobble up some wires and tether it all together like a string of sausage links.
Watch out for the Chinese-made Pullmors. Some run much better than others. The sheet metal Alco FA's and spur-gear driven steam locos run terribly out of the box. At best they sound like a coffee grinder. At worst, they jam completely. These engines have required extensive adjustments and work (including new bearings) to perform well. Next in line are the F3's and Geeps. They both use the same type of motor which performs adequately although significantly rougher than earlier US-made counterparts. The smoothest running motors in the Conventional Classics line are those found in the GG-1 and early cast frame Alcos. They are the only motors produced with almost identical quality to the postwar version including metal brushplate bearings. They run very smoothly and reliably in my experience.