Sridhar Katakam has just posted a thoughtful review of Google Hot Keys. He's a keen user of SearchKeys, so it's good to hear he agrees they complement each other, and his overall verdict is that it's "a useful add-on".
He also brings up some suggestions for improvements; being able to disable the term highlighting, turning off the hot-keys for moving between terms, and being able to go to the next page with a key command. I think those are all good ideas, I was planning on removing the term movement keys since it's not working as well as I'd hoped. I'll need to figure out a good way to term highlighting as an option, maybe in the top tool bar that's shown on all search pages. I think it's a good idea to offer a next-page key, I removed it to simplify the tool, but it does seem like that might have been too much of a simplification.
Thanks Sridhar for taking the time to write up that review! You should check out his blog if you're interested in productivity and key commands. He pointed me towards Mouseless Browsing, a Firefox extension for keyboard navigation, and has a lot of other tips on power surfing using Firefox.