Btw, I'm creating a brain prototype if you're interested in that sort of thing. Here's where most of the structure lies (https://github.com/crizCraig/brain/blob/master/src/neuron.py)
I wouldn't be so sure that they'd immediately be all that powerful though. Just because you're running on a certain architecture doesn't mean you understand the first thing about it or how to modify it - just think how long it's taking humans to understand and alter neurology.
Admittedly they might have a speed advantage, but who knows what they'll use that for - depending on the person and the environment they might spend the next thousand years taking e-heroin, or playing tick tack toe.
And, if they really are an insane sorcerer, do you want them to think that you're not going to respect their rights?...
Though, this does strike me as a good argument for only running the initial upload on crippled systems - no access to the internet, limited speed, etc.
If this is a person who has been placed in a computer, it's unlikely that they'll be willing to wipe out all their friends and family on a whim.
In other words, they'll be a motherfucking sorcerer. One who's just been through an untested brain-to-software translation, with possible sanity damage. Now, keeping in mind that we're talking about a motherfucking sorcerer with possible sanity damage, reread that list:
This is an extraordinarily bad idea. If implemented, it would almost certainly wipe out humanity.