as a beginner bassist hanging out listening to bands playing with stage volume and vocal PA I would always find a spot right in front of the 410 like a cat sits on the heater vent. I had no idea of the why I just thought I liked a lot of bass and that was the best place to take it in.That's a nice combination and a really killer deal, IMHO. The issue with mids for me was the off-axis response. In effect, they sound glorious from the front, but once you are about 40 degrees or more to the side, you only get the lows.
I've heard this many times live, and it's not an issue with the UL410 only, it is an effect one observes in all 310, 410, 412, and 415 designs, when the drivers are not in a vertical column. Sadly, it is just the physics of sound.
Off axis is indeed rubbish ime, particularly when on a short cramped stage with the damn 410 blazing away behind blowing up the room and I can't hardly hear myself for all the other racket going on.