Had a rented 50 Art last weekend and did a quick coma comparison in the corner of a full frame 6D. Old on the left Art on the right. F1.4, F2, F2.8. Ignore the brightness differences as it's just different areas of the sky. I should have done them on the tracking mount instead or paid more attention to location but it really doesn't matter for this.
Most all the 50mm offerings are so bad at it. The Art I'd hoped was even better than it was. Even if at the same time it is far better than the others, minus the Zeiss and the more expensive Nikon. In a way it's a 1 stop boost in less coma. Though yeah it is going to be sharper anyway. But if I was shooting something with street lights near the corners or with stars, I'd probably feel the need to head to F2.8. And if I'm at F2.8 I just about may as well be using the old Sigma. It's softer but guessing I'd maybe sell it for $200, making the jump $750 and I'm not sure it is that much softer when we're talking far corners here anyway. Not sure why I had it in my head the F2.8 Art coma result is what F1.4 was going to be closer to. Lenstip made it seem close to that. Or well lenstip coma at F1.4 looks like my star test between F2 and F2.8 I guess.
Anyway, just an example for those looking at getting it for that reason, which is probably many.