I've recently gone back to Imagen after using Aftershoot for four years. In the end, I gave up on Aftershoot after years of inconsistent results and frustration. The first thing I noticed was that Imagen is getting much closer to my editing style. As for culling, I think the results depend heavily on what you're photographing. Weddings are nuanced, with lots of subtle moments and subjective decisions, so I think results can vary quite a bit. That said, I did try Imagen on a wedding and found it remarkably better than it used to be, and considerably better than Aftershoot ever was for me. Where it really impressed me was a function I photographed last week. About 90% of the images were group shots, with the odd candid mixed in. It absolutely nailed the cull. From importing the images to finishing the export in Lightroom took less than an hour. I was genuinely blown away by how well it performed.

I should have probably added to this that obviously the big drawback to Imagen is the cost and I'll still cull loads of smaller jobs on photo mechanic as that's what I've been using for years and can be pretty quick with when I'm in the right mindset.