2.6 is great on the Levo. I run ~20 PSI, I'm ~185lbs.
I really hate the Butcher. Of course it depends where you ride. Where I am it's hard-pack, lose-over-hard, gravel, and sandstone. The Butcher (and also Eliminator) feel super sketchy to me on that stuff. I'm never sure when it will let loose and I don't like the transition to turning at all.
I have been riding the Purgatory for 5-6 years. I love the old design on the front, but they are getting harder to find. The new one works great on the rear, haven't tried it on the front. I would not claim they have the best grip, but they are super predictable. I generally feel like I know when they will let loose.
I recently decided to throw caution to the wind and get a Maxx Grip, DD casing DHF and DHRII. I have NEVER run a 1200-1300g tire, I have always tried to get away with the lightest tires I can. I'm starting to understand, the hype is real. I've only done two rides so far. The first ride I was too timid. The second ride I started to push things and found that I am absolutely no where near the limit on grip. I need to adjust my riding for sure.
For me I think the DD casing is overkill. The tires are too stiff for my taste. I could probably drop the pressure, but I think for next time I'll just go with a lighter casing in the front, and probably back to a Purgatory in the rear just to save 300g.
One unexpected side effect of the Maxx Grip compound: I have a constant peppering of sand and dirt flying into my face (and my mouth!), even with a huge front fender.
One other unexpected side effect of running 1300g tires; battery drain seems to be noticeably increased. The 25 mile ride I did today left me with 1 bar (all Turbo). The last time I did the same loop I'm pretty sure I had 2 bars left. It's not a HUGE difference, but certainly noticeable.