Pre-super shoes:
2:33
Post-super shoes:
2:21
Some improvements to training, of course, to account for that time - though in the most direct comparison I can find, I ran a 2:33 off a maximum of ~54 miles/week and a 2:23 off a maximum of ~51 miles/week (albeit in 5 days - was in law school in the first instance and a very busy law firm in the second), so I do think there is genuine, material improvements to credit to the shoes.
I've only raced in super shoes the past couple of years (like most). And I also got a lot more fit in that time so I don't think I can offer a valid comparison.
I do believe they help. A lot. However, I also feel the '4%' so often touted is probably a stretch. I know it's marketed as that. And people who have never raced in them can only benefit by extrapolating 4% from their PRs, but I don't think the actual physical advantage from them comes to 4%. Of course, I also think there's a psychological component too.