I got the re issue small stone having had an original in the 70’s. I really don’t know about the nano but I really do not get with this perceived volume drop. If you think about the full range of your unprocessed signal first then when the phase is kicked in it is going thro the sweep which is picking up part of the whole range of the original signal at any one time. I believe that you perceive a volume drop but in fact you are hearing it as it truly is. If you listen to when the sweep hits the bottom or full range, the volume is there. I am sure that there are those who would disagree, but for me this volume drop thing isn’t an issue.
As for the nano I can’t comment, but I can say Im really glad I bought the re issue (original) and I can’t hear any difference between this new one and my old original.