Go for it Toby !!
My 5year old pc is running Xr3 mill fine up to v10.65 which was a month or 2 ago when they stepped up a gear with the simulation which stumped my old Athalon 2200+ . In general though most pcs will run it with just a modest basic low end gaming card. Maybe for more complex models or complex 3d toolpaths you might need a little more higher spec Pc but nothing crazy!!
I too started with BC Wire and found the cad side a breeze to change over to Onecnc .( I reckon youd recognise quite a few names in the Onecnc Forum )