The large number of smilies wouldn't result in a bad look, or anything like that.
Of course - they'd have to be designed to keep the (TF) style (like current set we have).
It's a way the smilies are used that decides the final look and feel of the board.

Well, to be honest - what makes the forum looking more childish - a few more smilies per page or "sig" images added to each post?