Mt. Raineer is a non factor for me. It's won't be usable until the next Windows OS (longhorn) comes out anyway. AFAIK that's still a year or more away. Are you going to be upgrading to it right when it comes out? Probably not. Which puts us at 2+ years away. By that time you might want to get a Dual-layer burner anyway.
So all in all, myself I would even consider Mr. Raineer a factor in buying a DVD burner.