After looking into the subject and umming and aarring about it I finally bought one. The biggest problem was i could not decide by how much to go by (0.5, 1.0, 1.5 or 2.0 degrees). I mean, 1 degree sounded good but remembering its a hardtail and the head angle will always get steeper as it pivot around the rear wheel. But would 2 degrees make it too slack and hard to climb. O well one way to find out and go ball deep with 2 degrees.
I'ma big fan of long, low and slack and at the time of buying my trek stache there was nothing in the 29er hardtail market (seeing as they were for xc racing and nothing else) that really fitted the bill. The stache was the only bike that i could find that was slacker than 70 degrees but it was still only 68.3 degrees. Once bought it went through a constance change of components turning it from a xc bike into trail bike good enough for trips to Wales (tested at Penchma, marin and Brechfa by no means). With a few of these changes they did change the head angle to 68.0 degrees (130mm fork instead of 120mm (but seeing as i went from rock shock to fox and fox have a shorter crown to axal messament i don't think this has had an effect) and hans damp front and nobby nick rear tyre which i think they have had a big effect). The frame was becoming the limited factor especial with the head angle, que the A team music and the headset being fitted...
So first ride out the way, nothing particularly taxing with an urban loop with a few trail features chucked in for good measure. Defiantly feels different and more stable which to me makes it more chuck-able because of the extra confidence it gives. Only draw back that i can see so far so is that the top bearing does not sit inside the frame (this is so the bearing can be moved back to allow for the angle difference) so it raises the stem and bars up a lot more than pushing the front wheel further out lowers the head tube. This many mean a change in stem and bars to get it back to where it felt before hand.
As for the critical final measurement of angle i have ended up with a head angle of the fork at 65 degrees (3degrees different) which i can only presume it is because it is on a 29er and not a 26/27.5 (look up a bit of trigonometry to know what i mean, finally a maths lesions came in handy). Once i get a change i will try to take a few more measurements of the frame (bb height, wheel base ect)