I should mention upfront that I am a little biased, I love La Sportiva. I love them but only because they can handle what I throw at their products... Which just happens to be brutality each and every day.The shoe is pretty light while on my feet and I get great traction from them. When I first put them on they just made me want to run some place. I didn't care where, just somewhere.I have owned the Python and Futura platform for rock shoes and wouldn't choose another company to slip my feet inside. La Sportiva makes great equipment.
These are the lightest in the La Sportiva trail running shoe line. The tread gives traction, but the material is superlight. I use these when I want to do a quick run (less than 7-8 miles) and feel like I'm floating. Haven't raced in them, but I saw one guy at a 100 mile trail race (Zion 100) wearing them as he told me how he loves them. I've also used these as water shoes when vacationing with family around rivers and lakes-- drains fast, comfy. I've even swam in them when I want to have foot protection when I stand up in rocky water. Make sure you buy it a half to full European size larger than what you normally get, as they make these tight. I've seen people run sock-less in them, but my feet don't like that. (I do skip the socks when just walking around in them.)