Ok so a quick update...
I ran the wheels over the weekend.
Rode Llandegla Friday, plenty of air on the jump sections with mostly good landings... no problems.
Coed y Brenin Saturday, Fox trail ridden at mild pace with the odd balls out section, no problems. The beast in the afternoon, rode the whole thing in under 2 hours 35 minutes and gave it some stick on some sections, flowed others, at one point I was dropping my seatpost at the wrong moment so banged through the travel and felt the rear rim hit the deck hard... no air burp and no problems... phew.
Decided not to ride this bike at Antur Sunday but I did give it a full bore effort at penmachno Monday and I was pretty hard on the wheels.... no problems.
Just cleaned the bike and checked the wheels, they are straight with even spoke tension, there are no marks or cracks around the spokes or at the outer edge of the rim.
I ran the 2.35 Nobby Nics at 22psi front and 25psi rear. I popped a tube in for an hour before going tubeless, they both went up easily then with no air loss even without jollop.
Overall I am chuffed with my rims and wheels in general.
Groundskeeper... I have been tempted by the Eastons and at £359 at the moment they look good but I have never spoken to an owner that hasn't had to nurse the hubs and that is a best case scenario so I have resisted.