XPro2 Shutter speed /ISO dials

Questions to XPro2 users especially those who had a XPro1
I have two XPro1s and will update soon. Habitually use the Fn button to change the ISO.
How have you coped without the Fn button to change the ISO? Do you use the dials, if so are you happy using them? or do you use the Auto ISO?
The other option open to me is to switch to the XT2 which has a separate ISO dial, any comments?
Thanks for any help.