Andre Laradoe at DMax in Toronto and I both use the 250w without heat absorbing glass.
Between us we have made thousands of prints with the 250w on the D5's, just go through more bulbs. The speed is worth it.
10 Percent burn or dodge is exactly the same if you are using 10secs as main or 25secs as main.
I use the apeture closed down to 2stop or 3stops and find my printing times are generally around 10-15secs.
No problem to dodge and burn with this time.