Loved the sound of a Low D .. wanted to play one … but wanted to be able to play for a long time without pain in my hands. Reyburn Low D offered offset holes which allows me to play for several hours with no pain .. and cover the holes with my finger tips. Do have to use my little finger on the bottom hole but no problem. Also, finger tips make “working the hole” very easy.
I wanted a whistle that would still satisfy me when I learned to play it well and I think this one will. It is demanding .. and when I got it .. the “music” that I played was not of concert quality 
Takes a very light amount of air and the screaching on the second octave was enough to send the dog into flight. Am now able to play up to the high G with no problems and can hit the others on a fairly regular basis.
Purchased thumb rests from Susato web site .. and they help a lot .. feel like I have a solid grip on the whistle now…and they help me to find the holes a lot easier.
Everyone that has heard the whistle like the sound it makes. Say it is haunting … beautiful … grabs u … and etc. Tuning is adjustable and seems to be right on … according to several others that I play with.
I have played it for several hours straight and no clogging is to be noticed
I am able to play the slow songs with ease … faster songs .. with concetration and don’t know about the real fast ones .. haven’t tried them yet.
This is not a technical report because for one - I am still new in terms of months playing. In terms of hours played … been around for awhile. I can only report on how much I like it (which is a lot) and by how much others that hear it… like it … and that is a lot.
Placed an order for a Rayburn Low G .. with offset holes …recently .. and looking forward to receiving it as well ..
I stick with what I like
Jim