When we were pitching these ideas for a new server some months ago, I said characters should start at, and be locked at level 7.
The entire point was to remove leveling up as a concept, and make the game resource and equipment driven. Certain resources could be expended in order to obtain powered up items, and large lumps of this special resource could be used to provide you an additional level up to a maximum of 10. So basically, your max level was 10, but you started at 7. This made levels almost a non-factor. Your build was important, but your equipment was even more important, and no matter how "high level" you were, you could still be executed easily.
Level 6 is nice, but I don't like the idea of level 16 being the top end of that cap.
If level 16 is reachable, characters should start at 10.