Hey Dangit, those are good questions. It's not surprising that the channels sound the same with those controls maxed. The only differences between the channels (
when the drive switch is disengaged) is the tapers between those pots, so when they're maxed their active values should be identical. As stated, theoretically you should be able to get the same tones with the pots in their stock positions, but many of us found it difficult to zero in on that sound with the pots set up that way. Mesa tone and gain controls are so sensitive and interactive that it can take a long time to get THE sound you're after. A common complaint.
I can't emphasize enough: I think the biggest benefit to the mod is increased USABILITY for those users who want the two channels to basically behave the same way. Many users (maybe most) don't really have that issue for whatever reason, so they should just leave theirs alone.
Keep in mind: merely being able to "clone" channel 1 isn't really the point in and of itself. The point is that what many of us wanted was a Drive channel that had the
same character, at the core, as Ch 1. At least for me this meant maintaining this character
within the range of control settings that I typically use. For instance: I don't use my amp with the Gain maxed. Sure, the channels sound the same then, but what's the point of that?
Post-mod Ch2 still has scads more fat, rich gain than Ch1, it's only when the Drive switch is disengaged that they are "identical". Switch it on, and you're in saturated gain heaven.
Regarding the nasally/wet blanket thing, that is one of the complaints that the modders seem to feel is fixed with the mod. It sounds like you might be happy modding your amp if that's something you don't like.
Hair-trigger volume: This may be a setting-specific problem, but I do not have this problem with my amp at all. Again, usability: if that were a problem for me, I'd reverse the mod in an instant. I use my amp in situations that require very civilized volume levels, and I feel like I have pretty handy control over my volume.
I also found Ch2 needed a bump in setting compared to Ch1 after I did the mod, even as they were "cloned" tonally. By now, however, my settings and tubes are all different and I find my Ch1 volume is about a click or two higher than my Ch2 most of the time.
That brings me back to the cloning thing: again, it isn't really the point, it's more a way of referring to the basic character of the channels being more aligned. Usability. And I found that once I'd swapped all the Mesa preamp tubes out of my amp for a cocktail of different tubes, I actually can't quite clone the channels anymore. Probably just having two different tubes in V1 and V2 will make the channels sound slightly different. However: my amp sounds AMAZING. So I couldn't care less.
Hope that helps! You should probably just do the mod, if you don't feel comfortable doing it yourself it should be an easy one for a tech.