The "N" thing isn't what makes it unprofessional. The "Sticker" is. Also what makes it unprofessional is the intentional confusion of a brand. The entire POINT of a brand is to be easily recognizable for who you are and what you do. People will LITERALLY think that there are two different companies out there.
You are showing a staggering lack of understanding regarding what branding is. It tells me that you shouldn't even be THINKING about doing brand or logo design work for other people....
I'm not about creating a "brand" per se. I'm about someone seeing the sign, sticker, or whatever and dialing my #. I'd seriously paint, or letter the most ridiculous thing in the world if I could have my number put on it. Now with my customers I of course will do my absolute best to promote their brand, ideas, etc.. It's just that I personally don't care as long as they can see my number.