AtmaSphere Upgrade from Mk 3.1 to Mk 3.3

I have a pair of MA-1 Silver Anniversary edition amps that I had upgraded to Mk 3.1 some time ago.  I see they are now up to Mk 3.III.  Has anyone made this upgrade?  What did you hear different, and how significant was it?
@honest1 ,
I am glad you posted your experience. I am also glad that you found it a significant upgrade.
BTW, did you get the Caddock Resistor upgrade?
Thanks for that info.
I really wish I had done it while it was in the shop.
Oh well, something to add to my upgrade list...