Having spent a little time talking to Doug Jernigan at the CT. show, I decided to go for it and try out the p4 change he has been using "for 25 years and wouldn't go back"... I know Jimmy Crawford used it in the "Manual of Style", Buddy Cage lists it, etc. I ordered the gear from Carter, and popped it on on Sunday. it's very cool, a but heavier than the other pedals- I'm getting

Eb7 #11 13 -a bit muddy in open position but up the neck it's great.
Root on 9th string gives a nice I to bVII
Root on 10th, say at 12th fret, gives a nice I, then 11th fret p4 gives II7 #11 13 (Nice A Train progression!) normally found on p5 w/ 4th string lower but the voicing is a little better I think...

The missing major 7th voicing that was availble with the 4th string raise (with the nice min or 2nd on top) is now available P4+P5, strings 8 7 6 5, a fret below the 9th string root form (for C, it'd be 9th string root at the 7th fret, then drop down to fret 6, P4+P5, strings 8 7 6 5).

With the 4th string lower, you can get Eb triad and 6th voicings (bar position/open position)...

Bbm6/ Dbm7b5 strings 8765
Dbmaj7 7643 w/ 4th string lower

I know I am just scratching the surface, anybody else using this pedal? Wanna talk chords?

BTW I love "simple" country, the old shuffles and classic stuff from the Bob Dunn (rockin!) stuff through Joaquin (!!!) through the classic E9 playing...players like John Hughey, who can REALLY play both necks with equal fluency, astound me...as a middle-aged (44) guy who is new to the D10, I have to say that this world of music is fantastic, and the instrument has so many surprises...I'm happy to hear the first thirty years are the hardest, by the time it's easy I'll be numb enough to enjoy myself

I think it's a very cool change, I have fit i in once or twice, but it will grow on me I am sure.
I might want that to be a b13 above, but so far it's very interesting.

Funny, I had it one and then got the manual of style and went... hey wait a minute...