I just read the other half of your original post and I realized I didnt answer your question about the rhythm/lead channel, I myself keep both with gain all the way up and the difference is minimal between the two, the rhythm has a bit more of a sedated sound to it, but less hiss to it, while the lead channel is balls to the wall overdrive with awesome compression, its pretty much for giving your amp that little extra push to allow it to cut through the mix better for leads (hence lead channel) and for my clean tones, because the 5150's cleans are good but could be alot better, I use an A/B switch with a little marshall MG30 w/ reverb, its small but the cleans are freakin sweet and plenty loud