I guess I'm another voice "in the chorus"...
I've got two brother kittens, (18 months now) that were neutered at ~ 14 weeks old. One is taller/lankier and about 13 lbs. The other is "cobbier", but doesn't have the massive head of a tom (still has a "round" head) he's about 15lbs now and they're not done growing yet
I have had none of the male-associated behavior problems with them...no agresion, no wanting to "bolt" out the door to escape. No major fighting, no sparying/mounting behavior.
My cat from the shelter on the other hand (assume he was neutered as an adult, or at least past when the hormones kicked in)... He has a larger head, but.... He tries to bite/mount the other cats and can be quite agressive with them, he tries to bolt outside. I have been lucky that he hasn't sprayed inside though (crossing my fingers). Because of the difference in his behavior and the other cats, I can only assume that he acts the way he does due to being neutered later.
IMO, the advantages outweigh the disadvantages... I believe the number one reason for cats getting turned in to shelters is spraying / improper urination, so please consider whether or not you'd be able to tolerate that...as the odds of an intact male spraying are probably 99.9%. I've had to clean up pee spots from my cats UTI before...and believe me, even with a good cleaner (and considering that altered cat pee doesn't stink like intact male pee) it has been awful trying to get it out. I'm about given up on my futon cover...
If I were you, I'd get the kitten neutered, and if you really, really want a cat that looks like a tom...go to your local shelter and get a neutered adult male...but make sure you ask specifically if he will spray inside and/or be agressive with the other cats. Also, getting even a kitten with a rounder head and wider muzzle will give you at least a better chance of getting an adult with a larger head.