I've never done a side-by-side comparison, but there are usually some differences between AG and Extract if you want to make them look and taste similar. I would hope the kit companies would realize this and adjust the kits accordingly. After all, they are "supposed" to be clones.
That said, I would recommend proceeding with a Hopslam AG recipe with caution. Hopslam is probably considered an "advanced" recipe since it requires a lot of yeast and a huge hop addition and dry hopping. I mean, it's not THAT hard if you use a kit, but there are some considerations when designing a recipe to account for yeast cell count and hop absorption.
Other than that it's basically a IPA recipe with some honey added.
If you want the least chance of producing a different beer, then I'd recommend AG. My experience with Extract is that you need to use DME and late extract additions in order to get the color just right.
BTW - This year's batch of Hopslam seem to have much less pine in it than some years back when I first tried it. I think Bell's has adjusted the recipe over the years.