Yes, that's the idea, for first layers. I don't have anything by Under Armour, but my various Patagonia ("capilene") base layers work well. If it feels like too much warmth, try wearing it just under a vest, and skip the fleece.

A few years ago I got into mountaineering (of course I had to travel out of MN for it), and I was stunned to hear the guides out west deride fleece as much as they did. 10 or so years ago it was the best thing since sliced bread, for warm layers that dry out fast. These days, though it's just too bulky to pack, now that there is that thinner, water-resistant, and very durable "soft shell" Schoeller material out there. I picked up a light soft shell at REI last year for $99 that I've been wearing on my commutes this fall. Here's this year's model:
http://www.rei.com/online/store/Prod...ory_rn=4501868