KeywordSpy is appropriate for most Internet Market research companies. I would not suggest it for a corporate marketing department unless it's a company with a very larger budget. This is also not a tool for small freelancers even though there is a free option, to get the best benefit of KeywordSpy it's best to use most of its features and options and this can get pricey.
SEOGadget is ideal when using vendors like Moz and Majestic for analysis of your backlinks. It is not the tool to use if you need to gain more backlinks or want to increase your backlink. It can help you edit your backlink profile and understand where the links come from. It is probably ideal for in-house teams studying larger sites with lots of links and trying to understand their link partners, or an agency/freelancer that needs to import data from multiple sources to help clients with link profiles. It is not the tool to target new link opportunities, but with some ingenuity you could probably use it for this if you an access your competitor data. It's also good for anchor analysis which is something few teams really look into.
Most SEO and market research tools offer what KeywordSpy has but are not as detailed and in one place. Consequently, where you can do everything at KeywordSpy, with other tools you find you have to purchase multiple tools or subscriptions from different providers which also don't integrate with each other. KeywordSpy makes your research easier and more efficient.
This includes more data and makes backlink analysis easier because you don't have to build sheets and tables from scratch. While it doesn't directly compare (it uses some of these services) it is better suited for the custom analysis of data and that is a big help when you do a lot of data manipulation. It's easier and more streamlined than Knime, and Knime does not allow you to import directly from Moz or Majestic so a step is saved here. It can't do as much as Knime but most of the things you want to do it can do, and you can do them faster.
It is hard to quantify this realistically but it does save time and that is big
Importing data is a time suck, so the only real advantage here is the ability to do two or three imports instantly without downloading and visiting three sites, this could be expanded for even more ROI
We haven't had any negative impacts as this is mainly a time saver
