First off, the KSM27 is made in the U.S.A. I do think the Oktava's are pretty decent mic's, even unmodded. I had a pair that I ended up selling.
The KSM27 certainly wouldn't be my first choice for acoustic guitar, either. I definitely prefer SDC's on acoustic guitar, but for the price of a modded MK-012 I'd take an SM-81 or KSM141 any day of the week.
I do think, however, the KSM-27 is my favorite low end mic for vocals. Very smooth up top, and it doesn't sound like the cheap chinese mic that it isn't