I am now 4 days in on a pair of MTN LAB boots (thanks to Salomon UK !!), so here are some initial impressions:
(for reference I am 83Kg currently, size 28.0, previous touring boots include Dynafit Mercury, Technica Cochise Pro 130, Dynafit Titan & TLT5P, along with a variety of 120/130 alpine boots; conditions tested - hardpack piste, grippy piste, old soft powder, variable/crud... early season '15 in the Alps!)
Fit - seems similar to a Titan but possibly slightly tighter at the ball of foot and toe box. I never had to have a Titan shell pushed out, but most likely will with the MTN LAB
Buckles - The 2 buckle + powerstrap system seems very efficient at creating great hold of the foot in the boot. My initial worry looking at the boot was the lack of a 'middle' buckle, as with 2-buckle boots in the past (ie TLT5s etc) I have had trouble getting sufficient 'hold' of the heel back into the pocket, particularly noticeable when skiing heavier snow.
Boots with a view:
Walk mode - amazing! The range is very good (though this isn't a big factor for me as I don't typically go for uber-long strides even on the flat) but what really sets this boot apart is how good the walk mode is without unbuckling the main buckles (unlike the majority of touring boots I have used in the ast where most buckles had to be very loose to create a noticeable 'walk' feel). The lever to lock/unlock ski/walk mode is small but very positive.
Ski performance - very good so far - on a par with the Technica 130s, and considering these are 400gs lighter per foot (going on book weights - to verify on the scales when I have 10 minutes) this is impressive. Flex is stiff (good) but very progressive. Lateral rigidity seems excellent.
More to follow when I have had a bit more time in these...