I can't speak to Hypersearch, but I've used their Hyperweb mobile extension and Insight Browser mobile app. They're great! I've even had the chance to chat/work with Abhinav a bit, and he's a nice and sincere guy.
I also like this concept — I once toyed with the idea of a search engine/extension that would run a search in one engine by default and then notify you if other search engines would have returned significantly different search results. I'm excited to try this out!
I agree that it's hard to trust an extension that runs on any website, and I guess one way you could work around this would be to manually limit it only to run on the domain where you do your primary web searching. It wouldn't have the full functionality, but it would provide the bulk of the functionality — without most of the risk.
I also like this concept — I once toyed with the idea of a search engine/extension that would run a search in one engine by default and then notify you if other search engines would have returned significantly different search results. I'm excited to try this out!
I agree that it's hard to trust an extension that runs on any website, and I guess one way you could work around this would be to manually limit it only to run on the domain where you do your primary web searching. It wouldn't have the full functionality, but it would provide the bulk of the functionality — without most of the risk.