I took the opportunity last night to head out into the fields and try out for the first time a pair I got as a present 3 years ago. Having never used a pair before, and to be honest didn't think i'd get the change in Leeds, I wanted to see what the deal was.
I found that you move best if you walk 'heel' first and not like a clockwork robot. You tend to sink less. You need to get a rhythm going with your legs slightly further apart to move well, ( really works those buttocks ) and if you have to, you can get up to jogging speed quite well.
I would drop 2.5" -3" but i could put my gloved hand down a good 5".
Where I found them really working well is when you move over scrubland. You tend to walk over the vegetation and the snow as well, something that would be incredibly difficult without snowshoes, so makes walking where you want to go a more direct experience.
They do throw snow up the back of your legs and backside, wear waterproofs ( I didn't ), can be hard going at first ( turning round is fun the first time) but offer some support it you're about to topple over ( just like clown feet)
I may go out once more but it will be in darkness again as you look a tool in the urban set up and must be a magnet to abuse from hoodies.
Hope that helps.
JBTH