that nail stuff looks interesting... I have recently started playing the guitar again and my nails are a mess, soft and horrible. eating heaps of almonds always seems to get them strong tho.
As for mics: perhaps dynamic might be the way to go.... thinking about the sound of flamenco .... there is this bright percusive element that the km184 could ugly up.
how about beyer m201? I'm thinking percussivly here, I like them on congas and bongos: bright-ish without brittleness/hardness. Theres always the bloody old SM57, you never know. One of the coolest accoustic guitars I'v heard was recorded with a single 57 - mind you it did go thru a really kick ass pre.