I just got this and I love it. I've been using "Fighting" guards - $25 on Amazon and I was tired of getting replacement after replacement when the elastic bands wore off and there was rust on the loop for the waist band.
So, I decided to get this bad boy and it's awesome. First off the fit is amazing and I immediately felt more protected and secure. I still move freely, maybe even better since all my gear matches now. Really happy I bought this.
I'm 5'6", 165 with a 30 waist and the Medium fits perfectly for me.