I don't know if this is "good" news or just news but I tested the range of my MP3 player and class-D amp controlled by the LED remote system I showed on the other rolling stock thread.
I got 15 ft. reliably around a corner down the hallway. But the key is the performance was the same whether turning ON or OFF. The audio amp is class-D using the PAM8403 chip running at 260 kHz; there is no separate LC filter the board. The datasheet claims the chip is a low-EMI design but who knows what that means relative to your module's amp. But I can't imagine and class-D design having lower EMI than a class-AB style squeezing out battery-life is not an issue with rolling stock.
The LED controller remote uses a 3V coin battery with no external antenna so 15 ft. is pretty good. The 4-channel remote uses a 12V battery and has the telescoping antenna which together almost seems like cheating compared to the LED controller remote! I opened up the LED controller receiver and it appears to be a superhet design. From various listings for the remote, it is 433.92 MHz and that crystal on the right (6.7458 MHz) matches what various single-chip superhet IC receiver datasheets say as the crystal to use for 433.92 MHz. I could not correlate the "PP833L" chip marking on the so-8 receiver IC to anything.
So while I agree that you don't want to get in the business of designing RF receivers, this LED controller shows it's getting simpler with an 8-pin SO, a crystal, and maybe half a dozen 0603-sized passive components and no tuning-coil to mess with.
