The shoe needed to climb well on rock and reasonably well on snow. The plan was to be able to climb up to 5.7 on rock to avoid having to bring a pair of climbing shoes on moderate alpine rock routes. On snow, I wanted to be able to kick steps and plunge step with it. I had been using the Five Ten Exum Guide for a similar purpose, but the rounded heel cage on it makes plunge stepping rather insecure. Finally, it would be great if the boot could take a light strap-on crampon for the occasional icy patches.
After examining the options, I settled on the La Sportiva Boulder X Mid GTX.
The first thing I noticed about the Boulder X Mid was how incredibly lightweight the boot is. In my hands and on my feet, it easily felt as light as my Exum Guides. Weighing in at only 17.9oz / pair, the Boulder X Mid is actually just a bit lighter in my shoe size. While I certainly don't intentionally purchase heavy equipment, weight is not usually a major consideration in my gear purchases because light weight usually translates to reduced durability. In this case, though, I think I've found the best of both worlds.
The Boulder X has also met or exceeded my expectations in nearly every other respect as well. They climb quite well. The rubber is sticky but long-lasting, and consequently the boot smeared much better than I expected. Also, the lacing system allows for a fairly tight fit in the toe box when conditions demand it. Paired with a heavy-weight wool sock, they're warm enough for temps around 25-30F and the Gore-Tex liner is true-to-form as both highly water-resistant but breathable. Adding a mini-gaiter to my set-up has made these boots a tad warmer and basically impervious to water, snow, and scree. They even performed well in the most annoying of mixed conditions--one inch of snow atop slabby granite.
There are just a couple spots where these boots could be improved. The way the sole is bonded to the rand makes for a fairly floppy edge on the boot, requiring a lot more toe power when edging on small holds. A stiffer edge would make for easier climbing. Cutting a ridge into the instep of the sole would help them plunge-step a bit better as well. Finally, I found that after many miles in the boots, the insole is not quite as comfortable as my other approaches shoes and boots.
The La Sportiva Boulder X Mid GTX provides a great platform for tackling easy-to-moderate climbing on rock and snow while also providing the environmental protection of a light boot (at a very light weight). With a few minor tweaks to the soles, they'd be my ideal summer alpine boot.