I started with the Harmonicdyne Helios (still have), which was fine for what it was. The Zeus was a huge step up in quality (still have 2 pair). I tried the Poseidon and returned it; was not an upgrade to the Zeus IMO. I never tried the Athena.
Enter the new Zeus Elite that just appeared on the market. At $379 it represents only a nominal cost increase over the original Zeus. For that $29 difference you get 2 extremely well-built balanced audio cables (one XLR, one 4.4mm), which are easily worth multiples of the cost increment by themselves.
Comfort is very similar to the Zeus. Jacks are angled slightly backwards rather than being straight in. Minor niggle: the L and R are much harder to discern on the Elites than the original Zeus.
After letting them burn-in for 48 hours straight and then A-Bing them against the original Zeus, the quick and short of it would be:
“Take everything you liked about the original Zues and add low-end.”
Uneq-ed you can actually hear/feel the sub-bass now. It makes for a much fuller rounded-out bottom end to the sound across the board. The soundstage might be just a bit smaller than the original Zeus, but I didn’t find it to be a detriment.
Still in the honeymoon/acclimation period so opinion might shift, but initial take is very positive, as someone who really likes the original Zeus.
Is it worth upgrading if you already have the original Zeus? I would say yes, but it’s an incremental improvement. This instead of the original Zeus? 100% every time.