I have both... my UA-5 happens to be a W+ mod. I love the UA-5 with the LSD2. I love the AD-20 with the Naks.
I haven't run the LSD2 with the PS2/AD20 combo, but I expect it would be so freakin' bright I'd have to wear shades. That said, the LSD2 is a completely different beast depending on XY, Blumlein or M/S mode. In my limited experience Blumlein is brightest, XY is mellowist, and M/S is in between. Someday soon I'd like to try the PS2/AD20 with the LSD2 for an opening act, and the UA-5 for the main act, and post the results.