Looks indeed interesting, especially for the amount of items that can be stored in the search database.
However I use the free search engine provided by IBM together with Yahoo.
Omnifind Yahoo edition eats a lot less resources and has practically no dependencies, but the free version has a limit of 500.000 items. Go above that amount and you have to pay (dearly) for it.
Now I just visited the website from Omnifind and I see that support is not available anymore after 30 June 2011. That is a bit of a downer. Then again, I never needed support as the installation and maintenance is very easy to do.
So for as long as it runs I will not change, unless the performance of Search Server 2010 Express is dramatically faster. Do you know of any site/blog that did a benchmark test with several of the freely available LAN search engines?