I've got to say, you're handling a lot of negative criticism very well. Kudos.

I don't understand why anyone would feel let down by their signature - you need seriously low self-esteem to feel that your scratch on a page is something worth getting worried about. Will your audience be large enough? Are there enough of those people out there? Do you REALLY have 5000 customers? Paying customers?

As for graphology, it falls in the same area of astrology and spiritualism in which the proponent can toss out any reasonably broad trait, and someone will say "thats JUST like me!" - it's basically all bullshit.