I have a pretty strong opinion on this subject. Before owning my own business I worked for one of the top 3 banks in the US and they restricted EVERYTHING. No youtube, FB or even personal email. I hated it and EVERYONE turned to their cell phones to get the same content which frankly takes more time to type in my personal email info on a cell than to do it online at work. I'd say, save yourself the money on monitoring and let it ride.

I also worked for a company with an AMAZING culture.. (# 1 online mortgage company in the US for customer satisfaction) and they not only didn't block anything but they gave me 3 monitors to do my job. I streamed music on one or listened to youtube videos all day every day! My production at this company was nearly triple than working for Mr. Strictpants at the bank.

Take a page from Google and know that if you give your employees some flex time to do their own thing and treat them really well, they will get the job done. At the end of the day that should be all that matters is performance. My team accesses the web freely (as long as there is nothing X rated or illegal, I have no issue). I do monthly 1:1's with the team and monitor their production and quality like a hawk! As long as they meet the goals I set out for them and do the right thing by our clients, I don't care how often they check FaceBook.