As mentioned in the video, my pair is 1694 g, that's for the 25 inch model. In case you're wondering, I am 175 cm tall and bring around 65 kg on the scale, with winter gear that might go up to 80 kg for a three nights out trip including gear. At the moment we have powdery snow and dry, cold temperatures (it was -16°C as I shot the video). What that means is that the snow doesn't carry well, however, there is a clear difference seen in comparison to walking without snowshoes - I sunk in till I hit the ice or ground, while with the MSRs on I only sunk in a bit. As winter progresses and we get more wet snow, the MSRs will be the real winners - I wish I'd had them on my Easter trip last April.
The heel lifters are awesome. It is so useful and makes walking uphill a stroll in the park, it puts less stress on your achilles heel and I wouldn't want to miss it. I also run with them, and that's no problem either, works good. I feel that I am able to walk faster with snowshoes on, because I sink less in and avoid potholing. Three to four kilometers an hour are possible, that is double the speed if I am without. The only complaint I have, as mentioned in the video, is that I don't like the bindings. I think they're rubbish and I believe the new Speedlock bindings will be much superior.
In case you're wondering, yes, I also wear Trailrunners in winter. I'm sporting my Adidas Supernova Riot 2 with the Ascents, a perfect match and it brings the weight moved per foot to 1202 g. I'm not certain if that's still considered in the realm of ultralight, though I bet it's lighter than wearing boots and snowshoes.
I reckon that if you're walking much in the hills - like most of my UK outdoor blogger mates, or Philip from the US who also sports a pair - the Lightning Ascent would be the way to go. That heel lifter alone makes it worth it if you walk a lot uphill, you achilles heel will thank you. The question is just, buy now the MSR Lightning Ascents, or wait for the new ones in all black? That really depends on how much you think you're going to need them this season. Much of Europe and the UK got a load of snow this season and it might be a good time to invest into snowshoes, who knows if it is going to be the same next winter. On the other hand, if you can wait then you might want to consider the new MSR Lightning Axis, which are pretty much the same as the Ascents just with the better binding. If you think you can handle the binding (Philip can, he likes it as he said in his review) then get the MSR Lightning Ascents - all black is soo cool, and how did Joe say? "If Ozzy used snowshoes they'd be 2010 MSR Lightning Ascents."