I had a searx instance running for a long time and it's great when it works but the plugins for site specific searches break all the time and if you have more than 3-4 users with a high search frequency google blacklists your IP by throttling.
EDIT: It was located in a german street light 20km away from any of the users. Just to get the geolocation question out of the way.
It was more of an experiment than anything else there will be a talk about it and other FreiFunk (Open Mesh Network in Germany) related stuff at the next virtual CCC congress.
Note: since the version 1.0, searx stops sending request for 1 day when a CAPTCHA is detected which might help a little.
(I'm really interested by the results of your experiment)