This sounds like a great update coming to iShred soon:
We are putting the final touches on the next release of iShred and Guitar. The biggest feature will be adjustable string tuning. Each string can now be adjusted +/- seven semitones making it easy to setup Drop D or any other tuning. There’s a new icon in the edit screen (tuning fork) and when you choose it you can then adjust each string as you see fit for the song.
That’ll make for some interesting set ups on this app. Looking forward to that.