Old Dominion has steeper but rougher banks with the transition to infield mostly eating bumpers. Shenandoah Speedway is newer, smoother, and seems like you can go faster at this track. This is very friendly for slammed cars.
Old Dominion has gravel run-off so tracks can get dirty quick. Shenandoah is all pavement in the infield.
I wouldnt be able to provide insight on speed, as I only drift 100HP cars there.
It is definitely fun and worth going. It does eat a lot of tires quicker, so bring all tires you have.
Here are videos of past events at the same track to give you an idea of what the track is like. To provide HP numbers, the lime green e30 is 600HP, the white e30 is 350HP, and the Rising sun AE86 coupe is 100HP. Track friendly for a wide range of HP.
http://vimeo.com/46341170
http://vimeo.com/51333786