Rats are small, numerous, and dirty; hardly something people would keep as a pet, but even still, torturing/eating rats will make people look at us funny. Remember, the goal is to get out of this dump and acquire the necessary facilities to be the awesome man of science we intend to be. Though we may not have much reason for the police to jail us now, I'd rather maintain discretion, so that when we DO have something that can kill a city in a second, there's little reason for anyone to look our way, at least until its too late. And I assure you, if people will make a huge fuss about lab rat testing for medicines that will likely aid mankind, I fairly sure they'll object to frying lab rats just because we can.
Again, I don't mind getting some learning experiences in, but I'd rather do so in a manner that will yield better gains. Actually having a functioning method to measure and possibly manipulate rat brain waves will give us a working method to improve upon AND possibly new knowledge on rat brain functions. Jamming electrodes into a rat's skull will leave us with a dead rat and a better understanding of how much power is needed to fry a rat's brain.
Let's put the rat brain studies on the back burner for now, and instead focus on something more productive: increase our programming skill so we can make better, more readily sold robots.