Inside probably. Outside no.
Although using them in combination with other mics throws all bets out the window.
Not sure I'd run them at MSG unless doing so in combination with other mics, or just for fun to see if it worked. If I was going to try it I'd run them as spaced omnis PAS, leveraging their subcardiod pattern to increase direct-sound pickup over what I could get from omnis, with minimal angle between them for PAS you need sufficient yet not excessive spacing to get decent ambient stereoness.
The other way to use them is to leverage their subcardioid pattern by pointing them very widely apart so as not to have to space them quite as far apart from each other for good stereo, but that would typically be more appropriate outdoors where room reverberace isn't an issue. I wouldn't do that inside MSG if using them as a single pair.
It creates a huge "hole" in the middle of the recording.
Then space them less far apart, although that compromises other desirable aspects. Better, fill the hole and increase direct sound pickup by using a third, directional microphone in the center. Even better, use an X/Y or M/S pair in the center which will provide sharp center imaging to fill the hole. In either case, the hole becomes a feature rather than being a bug.
I think good old fashioned cardiods are the answer for Phish at MSG.
I think this is probably right.
If it helps, depending on the application I think of sub-cardioids as being either sort-of-directional-omnis, or alternatively as cardioids with extended bass-response and better far-off-axis response.