I love reading your thoughts, it's like reading my own.
Both Sam and Max are hard personalities to capture perfectly in my opinion. Considering they're fictional/cartoon characters, they have a set of very specific traits that make up their characters.
I agree with TT Sam's voice being monotone sometimes, but I must admit, TT sam's voice is embedded in my head quite a bit, to the extent that it really fits the character and sometimes i forget what hit the road sam sounds like.
that can't exactly be said about max, because, as you mentioned, he DOES act like a little child, as opposed to something of a semi-homocidal lunatic adult.
it's too bad about the cartoon sam's voice, really does sound like a buffoon. I really wish they hadn't put in that "girl genius" character, but other than that, the show grew on me until i actually saw that it's pretty out there as far as jokes go. You just gotta ignore the fact that they cut a few corners for kids.