I am not sure is there any restriction is signature for Hero compared to Legendary, but except that half dark blue coin the difference is only in the name and fact that users need some more time to become Ledgendary (for me almost 2.5 years before Merit).
Considering that these days is become very hard to become even Hero member, and fact that some Legendary members are perma-banned on a weekly basis, number of Legendary accounts will most likely only decrease with time.
I've never noticed that dark blue thing before. Now I feel an extra foot taller.
I'm not sure how I feel about how few people have ranked up since the merit system was introduced - https://bitcointalksearch.org/topic/log-the-ranked-up-members-congratulations-4850225
32 users have earned enough merit to be legendary and some of them may have been heroes when it was introduced. If I was a fresh arrival here that would look daunting. I think I'd put it in the back of my mind and just get on with getting on.