I do agree with steel... to a degree... but I'd additionally say it depends on your goal really. I mean a small boutique bat maker may only be looking to make a couple of hundred bats a year at most, and for this I think the main selling point is the quality of the bat, rather than the stickers. However if your looking to try and take on the GN's, Kooks of the world, perhaps like a Mongoose, then branding is absolutely critical and you'd definately need professional help then.
Also, for a small independent batmaker (as I am hoping to become!) cost is critical, and I'd rather put start up costs into the bat and get my product right, then hopefully improve branding/marketing as you go.
Anyway, no right or wrong I guess!
My opinion on Leo's stickers - I prefer understated stickers persoanlly, so like them!!