I have both, and I'll try to compare the two.
They both vape the same. They are very
similar in size, but the Chalice is a little smaller in diameter so I can use it on more of my REOs. It'll fit in some of the woodvil cups that neither the REOmizer nor the ERA will fit in. The
BIGGEST difference (and not a deal breaker, but a really nice thing....not worth an extra $110 to get, though) is that
the bottom of the Chalice is slanted down (like a swimming pool slants down in the middle to the drain hole) where the REOmizer (and the ERA for that matter) are flat. That means that the Chalice drains any excess juice back down the feed hole and into the bottle almost instantly. The others don't.
Therefore, the Chalice is NEVER ever messy. There's never any leftover juice in the Chalice or in the catch cup no matter how much you might over-squonk. The others CAN have leftover juice around if you over-squonk. Every now and then I'll have a drop of juice show up around my catch cup because I've over-squonked one of the non-Chalice attys.
As far as
taste, vapor, ease of set-up, etc. I find no difference among the gang (Chalice, ERA, A7, and REOmizer) EXCEPT that of the four, the ERA posts are closest together and are harder to get a coil to fit. Of the four mentioned above, the REOmizer has it's posts farthest apart. That's a good thing, to me. I can make coils with much higher ohms (more wraps) fit into the REOmizer because there's really a lot of space. I love that.
The
screws on all of them are different. The Chalice has flathead (tiny) screws; the ERA has hex screws, the A7 has really big (easy to see) Phillips head screws, and the REOmizer has tiny little Phillips head screws....tiny, tiny, tiny little screws. Argggh.
Of the four, the
Chalice is my favorite, and the the A7 is my least favorite (because it's so tall....and because it sometimes gurgles a little). I paid only $20 for the A7, so it was a bargain. I paid a fortune for the Chalice ($150) and I'm glad I have one, but won't be acquiring an arsonal

; and the ERAs were from two different co-ops and ranged from $55 - $72 each.
For the money, the REOmizer is the best bargain. It vapes as well as any of them and better than some, it's easy to set up, it's affordable, and it's cute.
I guess this is more than you asked for, but hey....
EDIT: Wanted to add that this is just my personal opinion, you understand.
YMMV