I guess I'm the "some other users".
I just got my 3000es yesterday. It won't pass subwoofer info to the sub out when run in 2 channel mode. Only way to do it is to use the DSP functions and have the receiver generate a subwoofer signal. I haven't tried it, but it doesn't sound the best to me. You can run it in 2 channel mode and it still has the front L-R Preamplifier outs working. So for 2-channel, you can set it up the same way I always have with my 2.1 channel playback system: L-R speaker outs for the L-R speakers (duh) and use the preamp outputs to go to the preamp input of your powered sub.
Only trouble with this is the LFE effects of a 5.1/7.1 movie soundtrack are not sent to the front L-R preamp outs on the 3000es/5000es, so you'll get no low frequency info sent to your sub.
So, for movies, you'll need to hook up the sub to the subwoofer output on the receiver, not the preamp out RCA outs.
Meaning, ultimately, there is no one way to wire up the 3000es/5000es for both 2.1 channel music and 5.1/7.1 channel HT. I'm going to make RCA input/output switch box so instead of pulling the wires each time I want to listen to different things with the 3000es I'll just need to flip a switch on an external switching router.
Bottom line, the 3000es/5000es is better used with no subwoofer on music (or that it is used only for 2.1 channel or 5.1/7.1 channel, but not both).