Well I tried a little bit and with a low volume setting and not slamming the front of the amp (I have a constant boost thing going on) I was able to get a pretty nice, but more importantly, a serious 'clean' tone out of R2. I didn't do much with it beyond that.
From what I've read, L2 is the channel voiced for scooped riffing. Have you managed to make L1 and L2 sound almost identical by tweaking their EQ's?
You can get them sounding pretty similar if you want, but generally I find this last description fairly accurate. L2 seems to by 'default' be a bit on the darker side. I'd say it was a bit 'scooped' compared to L1 but to my terrible ears it seems like a lot of the difference is in the higher side of the midrange. L1 just seems to naturally have a more 'present' sound, in addition to sounding more... well, more 'organic' if you want to call it that: a bit more of the 'acousticy' thing, or closer to say a single-coil sound when you're running buckers. Obviously they won't be identical, but backing off on the volume and gain for ch2 and dialing in a bit more of the upper-mid type stuff can get L2 quite similar to L1.
If you don't have much/any use for the other two channels you should be fine running the channels like that, though you might end up having to have the Ch2 master much higher than the Ch1 or something along those lines.
Obviously it's all personal preference but I'd generally recommend flipping the setup from what you want. L2 can churn out a really nice singing, creamy distorted lead tone that is probably on par, though a bit different, than L1 (L1 is still the high point of the unit, I think) but... I mean, R2 might be the versatile channel, but R1 is just godly.
But yes, I think your specified setup is quite possible, and if that's what you're looking for, I hope somebody that has more experience with the R2 as clean mode can help you out, since I've always used it for at least a crunchy/overdriven tone.
