I’ve used a variety of means to migrate from one Mac to another over the years:

1. Manually copy stuff over and do clean reinstalls.
2. Clone the HD from one machine to another.
3. And today, I used the migration assistant.

I imagine the migration assistant is great for most folks, but it’s less than ideal for web developers that have installed and configured *nix tools like SVN, MySQL, PHP, etc. I’ve had to reinstall these by hand – nice to be forced to upgrade I suppose. 😉

Based on my experience today, I’d recommend that developers use 1 or 2 above rather than 3. Your choice will largely depend on how much you want to maintain your current set-up rather than starting fresh, but also could be influenced by moving from a G4/G5 machine to an Intel machine. A clean install or migration is probably better than the clone option when changing to a different chip.