How do you find the mug otherwise? I've been really pleased (admittedly, yours flavouring the water is a rather large negative!) - the different shape and bigger size seems to make it a slightly more agreeable substitute for a cooking pot, and i'm not sure if it is just my imagination, but it does seem to come to the boil on a fair a fair bit quicker than my mk1 (which i still use alongside it).
I tried (notice the past tense there...) the Mark 2 and didn't rate it at all, really. The thing that annoyed me about it was the shape of the bottom: the Mk 1's bottom is flat, which makes it easier to eat out of and easier to clean, etc.; the Mk 2 has that curved channel around its edge with a flat section in the middle which, for me, just doesn't work. I'm not sure I liked the increased capacity, either.
The stainless Mk 1 may bring water to the boil slower, due to the conductivity thing, but it is, in my opinion, a hugely superior piece of kit and, for that reason, it retains its place in my pack as mug, pot and companion. I reckon that the creation of the Mk 2 is a classic case of, "If it ain't bust, don't fix it" but some, I'm sure, will love it and enjoy using it. I
would be interested to see a carbon copy of the Mk 1 made out of titanium but whether anyone will ever make it is another thing entirely!