I have one in my Bachmann Annie. I got the optional 1w amplifier with it.
You don't control the whistle and bell, but they go at while you're working based on changes in the speed, and it's always making appropriate sounds. Yes, the chuff stops when the whistle blows, but you don't notice unless you're listening for it. I've had trouble with light shining into the IR sensor. I've built a box around it of styrene painted black and black electrical tape.
I put the Dallee board in my mallet 'cause I wanted to control the whistle and bell myself, but I think I like the small scale board better as it has more character.
When I catch up a little on funds again, I'll put the QSI card in my mallet.
At $80, 90 if you include the amplifier, it's very nice. Installation is easy.