We have been using Boardvantage for about 6 years. I think they are now storing all info in Canada - they weren't when we first started using it. 

It has worked very well for us. Our Directors find it easy to use. On the back end it works well, although setting the permissions takes some getting used to.  We also do our Board surveys through the portal. However, I create my own reports to report the results to the Board, as I don't find their reporting on surveys to be helpful.  It's been very stable. We have fairly complicated Board and Committee binders, and you can create appendices for large documents. 

Whatever portal you choose...it is SO much better than doing paper copies and saves a lot of time.