The uneven confervision* rosters are the most controversial aspect of the new format. It seems obvious that it's harder to beat out four teams to get into the playoffs than it is to beat out only three teams. It's obvious, but I'm not sure it's true.
For one thing, if you're in a "7" confervision, you play your rivals 6 times each. If you're in an "8", you play three of your rivals six times, and four of them only five times. Assuming that those four teams are distributed randomly in terms of quality (they won't be, but over time it will work out that way), that's probably a couple of games against teams better than you are which you won't have to play. To put it another way, in some seasons, you will get to play more games against crappier rivals, and in some seasons you will play more games against better ones. That means that, in some years, "8" confervision teams will have a slight advantage over other teams in their own confervision, and in other years it will be a disadvantage. Whereas, in the "7" confervisions, there will no advantage or disadvantage from season to season (because those teams will always play their rivals the same number of times).
The advantage/disadvantage I'm talking about will amount to a couple of games that are harder than everyone else's (or easier, depending on the year), which I think is likely to lead to a penalty (or bonus) of a point or two in the standings. That is small, but significant (ask Dallas or Chicago, last year; or Philadelphia, Montreal and the Rangers, the year before).
And here's another thing. Of course, it's true that if you're in an "8", you have more teams to beat out. But it's equally true that, if you're in an "8", you have a higher likelihood of getting a team in your confervision that truly sucks. If this happens, that's five or six games against a bottom-feeder that no-one else gets. Obviously, this could work the other way (you have a higher likelihood of having an elite team in your confervision), but I think that is really just another way of saying "you have more teams to beat out." (It's only bad that there's an extra team in your confervision if that team is better than you; if they suck, yay!) In other words, it doesn't matter that you have more teams to beat out if you also have more teams that suck.
Which is another way of saying that, like the previous point about the potential of fewer games against elite opponents in your confervision, having the additional team in your confervision will be a disadvantage in some years and an advantage in others.
Here's something I don't know what to do with (yet). The "7" teams (because they have 23 non-rival teams) will end up with 46 non-confervision games. The "8" teams (because they have 22 non-rival teams) will have 44. What is the effect of having 4% more or fewer games where the stakes are less high because they're not "3 point games"? I'm agnostic, but it feels to me like something that could make a tiny difference over a season -- like a point here or there.
*conference + division = confervision. Or else, diviference.