I have both the UL1 and the Hubba.

The UL1 is lighter. The UL1 has a bit more floor space than the Hubba; headroom is about the same in both. The UL1 is about half again as wide as the Hubba at the head end, narrowing to the Hubba's width at the foot end. They're both side entry, with adequate vestibules, though I personally find the Hubba a little easier to get in and out of (I think it's because the Hubba is a semi-circle, while the UL1 has a definite high end and low end. Both have small rear vestibules, but the UL1 has a small zipper to let you actually use it without leaving the tent.

The UL1 door is hinged on the bottom - meaning you are crawling across it to get into and out of the tent; the Hubba's door is side-hinged, so it's never in the way. That bottom hinge is also tricky to open from the outside with the fly on and vestibule deployed: you open one half of the vestibule, then have to reach waaay into the corner of the closed part, and over any gear stored there, to get the door unzipped so you can get over it. But those are minor quibbles.

I've spent all summer trying decide which wil become my primary tent. I really want to like the UL1, but I'm finding myself leaning toward the Hubba. They're both very nice tents, and both work very well, but somehow the Hubba just seems a little more straightforward, simple, and "honest" to me.

I know the Hubba fly can be set up (with or without the footprint) by itself, using the pole; this makes a very convenient and quickly erected lunch shelter in the rain. The UL1 can too, but I've not tried it.

I also know for a fact that the Hubba can be pitched fly-first in the rain, keeping the inner tent reasonably dry. I'm not sure (but haven't tried it to know) if you can pitch the UL1 fly-first.

The Copper Spur is a really nice tent; you'll like it if you get it.