thats what got me on the Shure KSM and having a bunch of 57's around and a owned the SM7b...the SM7b imo is worth the money because its got the grill and all that housing/eq built in and the foam comes with it but the SM57 sound is so close and cheaper price. This is where a lot of disagreement/conflict comes is some say "whutta ya mean the dynamics
ARE FINE FOR MY VOICE!????" while others are doing some normal to quiet side or even whisper side of the spectrum saying..."my preamp is max'd and has a waterfall sssshhhhhsssss noise with my SM7 something must be wrong?"
The KSM27 and mics with -14mv/pa range are pretty well suited imo. They arent too sensitive to pick up the flys and fans in other rooms, while they arent so de-sensitive to require a bunch of gain....a happy medium, in my closet-crap HR no budget place. ymmv
again, I think if youre a screamingmachine and loud and strong vocals the SM7 /SM58 are tough and work well but for silent, low volume soft normal singing acoustic guitar strumming & wanting hifi sound of acoustic vocal combos LDC..
note: KSM27 is very close to the KSM44 (if you put on a foam pop filter 27 as SOS mentions, my tests were exactly the same, a big difference w foam..wow?!)
but then again...the SM57 might be more directional and cut out the noise of a noisey type room so that works better for you..... I went somewhere in the middle of crap-room and yet not too horrific so a LDC KSM27 is cool and doesnt pick up too much of the dogs barking outside.
Really for $250 you could get a SM57 and a KSM27 used(with $5 pop filter)and roll your own tests...
of course to confuse things more.... the SDC's are very cool mics for crisp and focus...