I do know that to process/render/encode m2t files it takes two to three times as long as standard dv-avi on my machine.
You can still edit dv-avi files on a P4 2.4ghz processor so for people looking for a means of not having to get a new computer that helps.
The price of a MiniDV is a bit less these days, making it a good buy for good quality.
Now I definitely agree that MiniDV is not for everyone, but for those just starting out that don't want to replace their computer it is an excellent option.