Alright so here's what I did:
I tested 1v1 and it was fine against an AI. So I went and tested a "fastest map tester solo" map, where I created 20 thors, 10 battlecruisers, and 25 marines for one side. The other side used 10 hydralisks, 5 ultralisks, 15 void rays, and some reapers and marauders, and a couple infestors.
The result:
During the battle, lowest framerate dipped to was 20fps. Highest framerate during the battle was 25fps.
Outside of the battle, with the units on the map and viewing one of the two armies, frame rates were between 30 and 45 fps.
Framerates topped out at about 61 fps in some situations that weren't important.
Settings:
1366x768 (maximum) resolution
textures: medium
shaders: medium
light: low
terrain: high
effects: ultra
post-processing: medium
physics: low
models: high
portraits: 2D
movies: low
If I reduced the effects down to high or medium, I bet I could have raised lighting to medium. And I'm sure physics could have been set to medium or even high without an issue since it's more processor-based.
In terms of the fan... it got loud. The temperature reached 85 degrees celcius... and it might've been higher (since I checked the temp immediately after I closed Starcraft 2). That's kind-of a high temperature don't you think? :-S
Anyways, overall, it was pretty good.
What I would do if I were to be testing this again later is set the terrain to medium and the effects to high. The terrain can really affect the FPS, and the effects can too in big battles. So those two things will likely bring the FPS up to playable in even a 3v3. Huge battles might get a bit laggy but it's playable.
As far as 1v1 or 2v2 play goes... one could get competitive just fine. However, do note that if battles get huge in a 2v2 (400 pop vs 400 pop), then you might not have ideal micro-management unless if you dipped the settings down.
For custom maps... I'd lower the settings just ever-so-slightly to account for the custom/large map.
Overall: I'm neutral on this. It did perform better than expected, which is great. As far as the i5/i7 on the 13-inch model goes, and the i7 on the 11-inch model, you'll get an extra 1-2 FPS in the games most likely (if not more)... so if you shoot for that, you'll be all set.
The one worry is the temperature... it's oddly high. I'm going to do some more testing. So long as it stays at 90 celcius or lower, it'll be in the clear. 100 celcius is the critical point that you can't go over, so it's desirable to stay well clear of it by 10 celcius.
