https://www.merlincycles.com/stans-no-tubes-arch-s1-wheelset-275-100822.html
After a lower budget set of wheels for the Whyte, XC riding, Swinley etc... 142x12 and 15x100 shimano hub, tubeless.
Not seeing anything that's taking my fancy more within the sort of price.... I could go a bit more if needed on cost.. but would have to be substantially better/lighter.
What about Crest S1s if for XC?
I pondered the same set (although the 29 version) for a while, I just couldn't quite get around the fact that they're almost 200g heavier than Arch Mk3 and cost almost the same.
http://www.chainreactioncycles.com/stans-no-tubes-arch-mk3-mtb-wheelset/rp-prod152389
Tragically I think I'm taking some Crossmax Elite over the Arch S1s (I'm stuck using Evans as it's Cycle to Work). The Crossmax are a similar width to Crest, but have a 35lb higher weight allowance and lower weight.
Have a lookout actionsports.de, for example, a whole 1lb lighter:
Hunt? I have a set of XC wides (29, xD driver, Boost) and so far they are unbelievable for the money (320) - light, go up easy tubeless, you get some spare spokes and a key in the box. Look pretty good in an understated way too.
Thye do a 29mm rim on 27.5 I think.
Mavic xa are decent price/weight/width combo. Nice pre installed tubless rim strip so no taping required.
Sorry for the hijack - brassneck, do the Hunts seem stiff enough? I looked at them but was a little put off by 28 spokes and I'd be after non boost too.