The vast majority of my DVD/BD collection is rated 12 or 15, while with games it's usually 3+/7+ (Over 60% of my game collection is Pokémon). Funnily enough, I have never been ID'd for buying an 18. The only time I was asked for ID when buying a DVD was on my 18th birthday when I was buying a 15 (it was the first Death Note live-action movie). In regards to certificate ratings, I remember how frustrated I was when the 12A was introduced the year I turned 12, when there were many 12 rated films I had wanted to see before then. These days, I tend to only think about the rating when it comes to showing them to other people (Obviously. I wouldn't want my 9 year old brother to watch Mardock Scramble xD). If I remember correctly though, don't some cinemas actually hold 18+ only showings of some lower rated films, purely because some people do prefer to watch in peace and quiet?
Regarding Tiger & Bunny, I wonder if Anime Limited are going to try and make their release look similar to Kazé's? That reminds me, I still need to buy volume 3...