If I understand this correctly: You love a 24mm lens and you are wondering if 28mm will be close enough to 24mm to make you happy.
Yep, that's what I'm wondering. Thanks for testing this and giving your input.
I had a Canon FD20-35 f/3.5L in the early days that drove me nuts. It was sharp but I couldn't put a filter on it at 20mm without vignetting. The front element rotated and Cokin filters were completely out of the question at the wide end, even when I zoomed to 24mm.
Then I got a Canon FD 24mm f/2.8 with a little 52mm filter diameter and I was in heaven. It worked with all my filters, front element didn't rotate and it was sharper to boot.
I found that 24mm was comfortable. Still super-wide but easier to compose with than the 20-35 at 20mm. I bought an EF24mm f/2.8 because I was so comfy.
Canon should make an EF-S 15mm f/2.0 L that's sharp into the corners for the same price as the 17-40mm f/4L. One that takes a polarizer without vignetting, with a 58mm filter diameter and a nice DOF scale. I'd buy that in a heartbeat. Maybe they ought to give it a 67mm filter: It's about time the 70-200mm f/4L had company. We need a razor sharp 15mm EF-S lens at any rate.