I don't think I'd enjoy reading something about Mycroft being smarter than Sherlock, but it is an interesting premise nonetheless. I just like my canon Sherlock too much. ; )
Actually, Mycroft is smarter than Sherlock even in the canon universe, in the books.
Which is why he's my idol. If you've seen the Jeremy Brett's adaptation where Mycroft shows up you'd also see his deductions are far more accurate than his younger brother's. But the reason that there's no "Adventures of Mycroft Holmes" is because that guy just HATES any physical exertions; he'd rather sit in his office all day and make his agents do the dirty job, while solving problems with his mind alone. Watching an obese guy all day without violent and gruesome adventures would be boring, no matter how smart or influential he is.
Though he is modest and physically lazy, he represents the British government, and at times,
is the government: he's got a lot more power than you can imagine. I'd actually say that Andrew Lane has done a pretty accurate job of portraying the brothers.
Don't forget that Sherlock is just 14 years of age at the time this scene takes place, and thus Mycroft is someone the little guy looks up to.
@Syna: Thanks! Lucid dreaming is a really narrow lane for me, with a big chance of falling in either side (absolute sleep and consciousness). But what's really amazing about it is that while in that state I'm capable of visualizing dreams in such vibrancy and detail it really isn't possible when I'm either awake or asleep, and also capable of shaping them to my will.