I know this was posted long before i could state my opinion, but i'd like to say something:
Firstly, you are SO lucky that you got to go to a youtuber meet up, i really want to go to one of those! Secondly, i think it's an original concept to put a huge subscriber picture on it but i think that it's just soo much! Tell what you do on the sign VERY VERY briefly in like 4 or 5 words and tell them "ask me about my channel" and then yeah you would still put a subscribe button on there just not so it takes up the whole sign, it;s not all about subscriptions, just a number, people that are like fans.. get them to know you and what you're about!