Yep, channels 1 and 2 are "improved" over the RK1. I'd still love to hear a direct, in person comparison of the two to see if it's worth the hassle to sell my current RK1 and upgrade to a series II or not? I really like my RK1, but since I got my AC30 and A/B it with my RK I don't use the RK's clean channel any more..... it's not bad, but the AC30 has the cleans I want and the RK has everything else I want.
Channel 2 set to Brit running 2 EL34's on the RK1 is probably one of the channels I have the most fun with, especially with a hot humbucker guitar. It sounds like an old Marshall about to explode if you set it up right. Turn the Gain to 100% and the Trebble to 100% and set the rest of the EQ to taste. Very "Old school" sounding and feeling (not a lot of low end, more of a top end bite). I'd hate to loose this channel if the RKII doesn't have that sound in it.