I have a brooks champion flyer, sprung saddle which I have used in the past for touring on a converted mtb.However, I have read recently on Sheldon Brown that they are best suited to bikes where the handlebar is higher than the saddle. Is there a recommended bike setup or limit for handlebar to sandle height difference for using this saddle? I've got this in my head now and I cant remember the difference between handlebars and saddle I had when I was using the saddle for touring. Now I want to use the saddle for commuting but my mtb has a different cockpit set up and wanted to get third opinion!
I assume you are talking about this page: https://www.sheldonbrown.com/saddles.html
I think what Sheldon is saying is that upright riding positions - with the bars level with or higher than the saddle - would benefit from a sprung saddle. I don't see anywhere where he says spring saddles are not suitable for use with lower bars.
If you like the saddle and it works on your commuting MTB go ahead and use it.