Question
Evictor Strobe Light Squirrel and Rat Repeller

Do you have knowledge if this strobe light technique will be useful in ridding squirrels from the attic -- as another option, I've read your other advice and that from others.  Its expensive $240, so its not my 1st choice, but one I'm considering as back-up.  Thanks!

Answer
I am not aware of any peer reviewed research that supports the claims of the manufacturer. THat doesn't mean it doesn't work. It just means I haven't seen research to show that it does work. The company claims a lot of anecdotal support. I am skeptical.  
Even if the light is bothersome to squirrels, what is to stop them from moving down into the wall to keep away from the light?

For 240 dollars you may be able to hire a professional to do the job and close the hole.
YOu can certainly give the product a try. Just make sure you know if they have a return policy. If they don't, I would advise against it.
Vendors can be found at http://icwdm.org