Here's a funny one.
I used Direct CD 2.0 to format a 24x US-RW disc on a 52/24/52. I had to give up and stop it after 2 hours!
I can format a 10x HS-RW on a 24/10/40 drive in 10 mins!
I'll try formatting the 24x RW in the slower 10x drive and then put it back on the faster one to see how it goes.