Photoshop: Allow for a larger feather radius (the current 250px limit is too small)

I'd like the feather selection function to support a larger radius, up to 500 or 600 pixels.
I use it to create custom vignettings for the final version of my photos, with a value around 10% of the biggest dimension of the photo (so, for a 2000px wide photo, I'd use a 200px feather). The problem is that it only goes up to 250px, so to get the look that I want I can only go up to images 2500px wide/tall. I know I can re-apply the feather function (or do a combination of feather and expand or contract), but it messes up the shape of the elipse or circle. The feather function is pretty fast even on slower computers, so it probably isn't very complicated to implement a bigger radius support (although the computational complexity might progress with a x^2 ratio, I don't know). Thanks!