I put mine on the front (see below pic)...I will admit that it took some getting-used-to as the lettering was in my upper periphial vision, but that only took a few days and now I don't see it all. Mine is 3 1/2" tall - your'* looks to be pretty close to what I have, btw.
Another thought to consider... being the only maple red pontiac in town with a front windsheild banner proclaiming so...folks know it'* me when they meet me on the road... which is cool at times...I get a lot of "hey! I say you the other day going down such and such street." It'* not'* so cool if I prefer to be in stealth mode
Basically, I can't blend in and be annoymous anymore... but that'* okay... I prefer to stand out in a crowd.
It all boils down to your personal preference!