As is often the case with Arc'teryx products the Bora 2 is a new look at outdoor technology.
The boot's durable, seamless, single-piece thermo-laminated uppers are partnered with interchangeable stretch liners in what the company calls 'Arc'teryx Adaptive Fit' as it provides the wearer with the ability to modify the boot to perform in varying climates and conditions.
The stretch Gore-Tex liner delivers waterproof/breathable protection in wet conditions, at the same time as its highly air permeable stretch micromesh fabric also provides ventilation in warm, dry environments (an insulated liner for cold conditions is available separately).
These interchangeable liners are made from stretch textiles that cushion impact and conform to the shape of your foot, and separating the liner from the boot shell allows the Gore-Tex to extend to the very top edge of the Bora 2's cuff, adding to the waterproofness and, because of the elastic cuff, making it more difficult for water to get in over the top.
The outsole, designed by Arc'teryx in conjunction with Vibram, works in tandem with the moulded EVA midsole to combine the agility of an approach shoe with the stability and protection of a mountaineering boot.
In use the Bora 2 is quite stiff although it doesn't require any real breaking in, and although very lightweight (600g/pair) it does feel that it's providing plenty of support and protection.
In use however, the snug fit of the inner boot just felt a bit too warm, even a little sweaty - though it was a plus-20C day when we used the boots. That said the idea is that the Bora 2 is versatile enough that you can use it at any season depending on the liner you're using.
It may just be that the new concept of liner and boot needs a bit of time to get used to, but for now the jury is still out as far as we're concerned.