All Mountain Bike? what is it?

Hi Harley, and welcome to Vital! Your question is a bit deep, and the answer could be too, but I'll try to guide you without making you read a whole novel in the process.

A mountain bike presents an inherent compromise between how good it is in fast, steep, or technical terrain and how well it does on longer, flatter rides and/or bigger climbs. In general, favoring one side of that equation means giving something up on the other side (talking about design choices regarding frame geometry and components, mainly). Now, the problem is that a lot of the time, the fast, steep, and technical trails are accessible via...you guessed it, a long climb. Now, as you might have guessed from the name, all mountain bikes are designed to be pretty good on both sides of the hill...and they are!

You state "you're not sure you need all that" travel...which tells us you don't really ride very technical terrain. If that is the case, and also how you intend to keep it, then yes, a 150-mm travel bike like the Norco Sight you have been looking at might be overkill. However, as with many bikes in this category, frame geo and components have gotten so good that you don't really have to make all that much of a compromise anymore. With that I mean that bikes in this category are quite easy to live with as your "daily driver", even on flatter, less demanding terrain, because their weight is kept in check and modern suspension components deliver a fun and dynamic riding experience on all kinds of trails. And then, when you're ready to tackle bigger stuff, you still have a bike that can do it. For any rider who aspires to pushing themselves a bit and discovering more technical riding, I would wholeheartedly agree with starting with a bike like this Norco.

On the other hand, if your goal is riding XC epics with your buddies, and you're worried about keeping up over a 50-mile day out, you would be better served with a shorter travel, lighter, "trail" bike (sort of 130mm travel...maybe even an XC marathon bike)...so it's up to you to properly identify the kind of riding you do (and want to be doing), and chose your weapon accordingly.