I had an R before the Z and found the R to be a much better fun bike.
The surging and popping on the R just gets on your tits after a while and after having a ride on a Z I bought one as it was the lesser of two evils
Both on Distanzia's and the R just seemed to handle better than the Z regardless of suspension fiddling with both.
The R rags your arse in less than an hour and the Z does my knees on longer trips, I'm 14st and 6ft.
I have an Airhawk on the Z which does help but I'd like to try a Touratech high seat if I get the chance to sit on somebody's with one fitted before I blow £400 to try something which may or may not work.
My R was bog standard and the Z has only had handguards and the AIS blocked and a front wheel from an R and a high front mudguard.
At the end of the day I'd say the Z is the better tourer as it has a more useable seat and less surging in standard form, can live with the buffeting as my other bikes are naked and each has a degree of neck blast.
If I'd known about the Kev mods before I swapped bikes I would almost certainly have stuck with the R and had a seat builder do something to make it more distance friendly.

Pete.