We've been looking for a search tool for a very long time. And we ended up on Search Boost. It's templates are highly customizable and the search is blazingly fast. One of the things I liked the most, was the ability to make custom searches from my own tables, it event makes you display your own custom fields!
And I just have to talk about the support.. What the team at DnnSharp do for their customers is beyond me. Just simply amazing! Support is blazingly fast, and dead on accurate. So if you need a search enginge on your site, look no further.
Dynamic Forms are nice, bit the Opt In 4.0 module module is really more like an early beta version. We have made Datasprings aware of this, but the fixes takes too long time. It should not have been release yet.