Peter Lwrote a review of Maxxis Ardent Race Tire - 29 on November 3, 2015
Familiarity: I've put it through the wringer
There is a lot of fast hardpack trail around here, and I'm an XC racer, so I've been riding ikons front and rear for awhile. They're fast but don't have great traction when you get a little bit of looseness.
When I saw the ardent race it seemed like a good way to get a little more front grip without much of a weight or rolling resistance penalty, and I was right. Have raced and ridden this with an ikon rear all summer and am really happy with the combo. It's fast and I have more grip and cornering confidence.
Despite getting the non-exo version I have not gotten any cuts, where my non-exo rear ikon has not done as well. So I think if you were going to use it as a rear tire with a regular ardent or something, go with the exo casing.