Having been a Black Diamond headlamp user I recently bought a Petzl Tikka XP and here are a few comments and comparsions.
~ First off ; this Petzl has a diffuser feature that works very well spreading the light over a wider area and softens the brightness which is especially nice when at shelters .
~The beam on the XP2 seems better ( illuminates a brighter beam ) than the Spot .
~The night vision red LED works great for reading or locating objects close by without being obtrusive. No difference there in comparison.
~ I also like the suggested longer battery life , up to 80 hrs(high beam), 160 hrs ( low beam) but obviously can't comment just yet on that.
REI stores have this Petzl headlamp on 30% off at $37.93 thru their website at www.rei.com .