I'm going to be a bit of contrarian here...
I currently have two different pairs of boots in the rotation. The main pair is a relatively snug, but still comfortable fitting boot that fits best with what most would consider a thin sock. Down to semi-cold temps, these are fine. They don't pinch anywhere, and I feel my blood circulation is still quite good in these boots. I wear these boots 90% of the time. (Way better than the rock hard, ice cold boots I used to use when I regularly raced - don't miss them at all!)
I've got another pair where the liners are a bit looser (a bit older too, so they're packed out a bit more due to age). These are loose enough for me to comfortably wear a thicker pair of more insulated wool socks. On those really cold days, when I pair these boots with the thicker socks, the boots are noticeably warmer than my main pair. Sure, they're not as precise at the limit as my main pair, but I'd not call them sloppy at all. A bit more insulation + a bit easier blood flow = warmer feet.
Now, one could say the looser boots just have other properties (e.g. liner insulation) that make them warmer, but they're similar enough that I don't really think that's the main factor.
I currently have two different pairs of boots in the rotation. The main pair is a relatively snug, but still comfortable fitting boot that fits best with what most would consider a thin sock. Down to semi-cold temps, these are fine. They don't pinch anywhere, and I feel my blood circulation is still quite good in these boots. I wear these boots 90% of the time. (Way better than the rock hard, ice cold boots I used to use when I regularly raced - don't miss them at all!)
I've got another pair where the liners are a bit looser (a bit older too, so they're packed out a bit more due to age). These are loose enough for me to comfortably wear a thicker pair of more insulated wool socks. On those really cold days, when I pair these boots with the thicker socks, the boots are noticeably warmer than my main pair. Sure, they're not as precise at the limit as my main pair, but I'd not call them sloppy at all. A bit more insulation + a bit easier blood flow = warmer feet.
Now, one could say the looser boots just have other properties (e.g. liner insulation) that make them warmer, but they're similar enough that I don't really think that's the main factor.
