Hi, I have had one for about a month. My mare has always reacted to being girthed up by trying to nip, she no longer does this. I would say that it was worth the money as I think she is now more comfortable.
I've got a mare who is extremely sensitive to being girthed and will squeal and get upset even before any girth is even done up. I got her the Equi-soft GP girth and she's been a lot happier than with any other of the (expensive) girths I've tried so far. Results have been so good I've ordered her a dressage version, I currently have the Amerigo normal shaped dressage girth (https://www.smartpakequine.com/pt/pt/amerigo-special-dressage-girth-4455) but she doesn't like that being done up. I will be using the sheepskin pad in winter and think she'll like that. I'll probably get some sheepskin covers made up for the long strap bits, just to make them as comfortable as possible.
I tried the Equi-soft GP on my 4 year old today and although he is a lot less sensitive than my mare is, he seemed very happy in it and there was no reaction at all to tightening the girth.
A lot of the prestige manufacturers seem to be making girths now that spread the pressure over a much wider area on the sternum, my saddler thinks this is one of the reasons why the Equi-soft is liked by my mare.