Hi dac1,
I’m not in Devon but I can tell you the Strive’s a great bike. With regards to sizing in my opinion the only thing you need to be aware of is the top tube length. I’m 5’10 and initially the Medium felt cramped to me, although I do have gibbon like arms!
When comparing the Strive to other 160mm/180mm All Mountain/Enduro bikes you’ll see a short cockpit with long wheelbase is par for the course (Alpine 160, Nuke Mega, Patriot). If you’re coming from a smaller travel XC bike they typically have a longer top-tube with a more stretched out geometry than these types of bikes.
On the trails the Strive can handle some pretty big stuff although its just as happy zipping along single track. The suspension feels very plush and yet supportive on the climbs, magic really. The Pro-pedals easy to reach and transforms the bike from trail light to down hill bump sucker.
Good luck with your decision.