new mac pro swapping old mac pros system drive

[mactree]

I know this is just the cardinal rule of what not to do. But really, I have a new mac pro arriving today and I'm swamped with work. I'm very tempted to just swap the system drive out and hit the ground running on my new machine rather than spend 10 hours doing installs.
Believe me, I would love to have a fresh install of everything with out all the old files I don't need clogging up my system.
But just how bad do you guys think it is to do this?

 

[aibo]

http://www.apple.com/pro/tips/migration.html

 

[mactree]

thanks for the site. I gave it a shot. But the migration failed when trying to copy the user documents folder. This is when I first started up the machine. I thought, ok fine I'll just skip that part and do it manually, but now when I launch migration assistant, it 'only' gives me the option to migrate the user accounts.. no applications or system files, nothing. where as the first time, all of those were available.

both machines are up to date on software, I repaired the permissions. I can't think what else would cause migration to fail.