Can anyone enlighten me to the major differences between this and the Nepal EVO GTX? I know this is leather and a bit heavier, but I'm looking for something that can handle long approaches, ice climbing, all-season mountaineering, etc. and I'm wondering what's the better choice.

The Nepal Evo Gtx are a fully rigid mountaineering boot even more so than these. They are warmer and just as stiff as these, with stiffer uppers and more ankle support, but heavier. They are more of an all-around boot, it's true, but that just means they'll be great for everything whereas these might not be enough for some conditions. These are lighter and therefore more nimble for vertical stuff, but the Nepals will handle long approaches much better and still be great for steep stuff. If you want an all-round boot the consensus is clear: get the Nepal Evo Gtx.

The Nepal EVO GTX is much softer, with a 3/4 shank, and is meant as an all-around 3 season mountaineering boot. The Trango Extreme is fully rigid, with a full shank, and is designed for full-on vertical endeavors such as 3 season ice and mixed climbing.

I'd go with the Nepal Evo, they're both insulated and (mostly) intended for vertical endeavors, but just going off of the customer feedback, a lot of people use the Nepal Evo's for summiting, and trekking in.