I notice the amounts posted for changing color as $1000 - $1200, think how little it is to change back.... $200 - $300, that brings it down to $600 - $700 per change. And that was only one cycle.
It appears to me, that panel removal and replacement is more involved on the 451 than the 450. Be prepared to pay for maybe an additional hour.
To me, the enthusiast will be changing panels his/herself.
Imagine going into work on Monday morning; "Hey, did you buy a new car already?". "No' I just changed colors myself Saturday morning".
My wife took a fender from our car into a dress shop and said; " I'd like to see some dresses that go with this".
In Europe they had problems with ID (Colorwise), it was solved by only using the tridion color.
Donald LaFavor