1. MTH PS/2 or PS/3 locomotives already have excellent smoke performance, including good chuffing, so it's not needed for those. PS/1 locomotives don't have a chuff switch, they generate the chuff sound based on track voltage. As such, I have nothing to sync the chuffs.
Of course, an MTH PS/1 or conventional with the stock smoke unit that's been upgraded to TMCC is a candidate, the Camelback that I did my original test installation with is an MTH locomotive with a TMCC upgrade.
2. If the LC+ locomotive has a chuff switch to trigger the sound, the S-C would work fine with those. Truthfully, I haven't had an LC+ locomotive apart to see if they use a mechanical switch or some other method of triggering the chuff.
3. I originally build a voltage doubler module for conventional operation as the S-C was designed with command in mind, and I truthfully didn't really consider conventional. It turned out that there was a flaw in my thinking with the voltage doubler, and at higher track voltages it's output exceeded the capability of the power module on the S-C board and promptly killed it!
I went back to the drawing board and have a simple fix that allows conventional operation. It's embarrassing that I didn't consider it previously. I add a 1000uf 35V capacitor across the on-board input filter capacitance and the S-C board works fine down below 5V on the track. I just put a few inches of wire on the capacitor and it can be placed anywhere in the shell to allow conventional operation.