Hi and welcome to the forum

I'm 6ft 4 and have owned both xtr and xtz. I'd say the tenere would be better suited to the road but can still handle plenty off road where as the xtr can still do the road stuff but just not as comfy as the xtz but as it's a good bit lighter is easier and less tiring off road

But as you've found out with the gs best way to find out for you is test ride both.

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Plough on