Well I think the w-mod UA5 is killer. And Doug does change the chips that drive the ADC:
from:http://www.oade.com/Forum/Tapers/viewtopic.php?id=8&t_id=11
"While the RCA inputs do benefit from the MOD as the chips that drive the ADC have been changed, it did not get the total re work the XLR inputs got."
Basically I think the AD in the UA5 is far superior to the m1/D100 or the DA-P1, and I own a wmod UA5, a D100 and a P1. I think the Analog inputs on the stock UA5 are so poor that you need the mod to get the full performance of the AD even when running an outboard pre. If you run xlr in and turn the knobs all the way down then you are basically utilizing just the AD in the UA5 with the benefit's of Dougs signal path upgrade.
Doug himself told me that he thinks the UA5 is better than the modSBM-1! I'm not saying you should just take his word for it, trust your ears, but thats quite a statement.