I have that exact setup, an RS-3 with QSI--and I really like it. The sounds are to my ears excellent--very "dimensional:" and they change with the load on the engine--both in volume an in timbre.
I run mine on constant track power, so the start up is different because of the CV settings. I changed them in accordance with the directions but I can't remember the exact values. I also monkeyed with the starting viltage to smooth out some of what I describe below.
The one thing I don't l about it is that with the engine, and only this engine, the start up is rough and a little jerky. The front headlight flicker. I don't notice any cab light flicker, but the front headlights flicker as it's starting, but once it's up to say two scale miles an hour they are on solidy. Tinkering with the CV startup voltage smoothed this out somehwat, but it's still a little rough--not a big deal, but a little rough.