Now that I'm Mr. Fusion Guy, my 7-string guitars have been sitting in their cases for a long time. I simply have no use for a low B string anymore.
I've been toying with converting the KXK Sii-7 to a high A-string setup, in order to really take advantage of its 27-fret layout. However, since I'm tuning most of my guitars in D standard now, I thought it might make more sense to have the KXK tuned D to G in order to have it fit in. It turns out this has the added advantage of not having to buy those crazy expensive Octave4Plus strings in a .005 or .006 gauge. I bought a couple of D'Addario .007 strings today and was able to tune it up to high G with no problems. Since I use 9-42 strings for the rest of the guitar, the high G obviously has a lot more tension than the others, and I may still buy some .006 strings from Octave4Plus if this becomes a problem.
In a sense, however, I don't really have a high G, but rather a low D. My tuning is G standard + low D: D G C F Bb D G. My favorite open-string chord voicings sound very interesting transposed up a step and a half. I tune this way because I conceptualize the neck from the top strings down. It's much easier for me to adapt to an extra low string than an extra high one. The weirdest thing is having four unwound strings on the guitar.
Sounds really interesting. I've not had a 7 in quite awhile now, but this would be very interesting to try, as I'd most likely get more use out of it than a low B. I have been playing a lot from D to D.