Pete
I get what you're saying. Maybe I'm a nitpicky fanatic when it comes to the Hudsons, but I just don't want a Hudson sounding like an N&W J or a PRR K4. I'm not looking to turn a conventional engine into a 100% Legacy locomotive, just one that sounds reasonably like its prototype - remember how ticked everyone else was when Lionel gave the Legacy Blue Comet that high pitched sounding whistle in 2012? As long as it chuffs, rings and whistles, and sounds reasonably accurate, I'll be fine.
Believe me, I would go for any of the older, cheaper RS4.0 boards from older Hudson locos if they existed at Lionel's parts department, but that isn't so. And, no, I'm not a hater of the ERR sound kits - the large one suits the MTH Blue Comet locomotive I'm upgrading just fine.
Like John said, looking over the exploded diagrams, the sound systems look almost as modular as the older RS4 and 5 systems.
