Really try before you buy, test fit, find a MX store near you.
Did try some some Asterisks out, they have been revised and the old model can be found a bit cheaper.
My boss did a proper job on one of his knees, he has gone for a Fox Pod single unit and loving it, he has worn it for xc rides but has built the muscle up and now uses it for DH messing about only.
Fit is everything, size is important, and it took a couple of short rides, walking about to dial in the final fitment adjustments, at first the boss thought he made a pricey mistake as very uncomfortable, now he dosen't really notice it, and wears it all day uplifting. An undersock (looks like an armwarmer) will add to comfort and wicking away of sweat.
Not sure on the rebuildable nature of the Pods, but the Asterisks are fully rebuildable, Madisons are the importer so really any bike shop can get them in, but MX shops will have more experience with them and fittment advice.