Have any of you tried a thing called the Third Hand Capo.   My brother bought it back from the States for me over 15-years ago. Basically it is a capo with an individual cam for each string so that you can release any string of your choice but when you play a barre chord the tuning reverts to standard.
I have used it in writing many songs. It gives a perfect mix of open and standard effects....I wonder if it is still being manufactured and why nobody has mentioned it.   By the way, it also works on banjos, mandolines et al.....M