This just arrived today. First impressions are very positive. Compared to the pictures of early authentics I've seen on VU, the machining is much better, clean threads, great fit and finish all over.
The top fill implementation is straightforward, very much like Kayfun V4. Airflow ring fits perfect, much better than my Silverplay and a little better than my Goblin. Juice channels are deep and smooth. The deck diameter is bigger than Goblin with the same size and chamber threading as Orchid and Silverplay, and the tank specs are likewise compatible with those plus the Kayfun series, so it will add very nicely into my compatible parts possibilities.
One subtle detail about the deck: the PEEK insulator around the center post is recessed therefore less likely to be fried by a tight low coil build.
Everything is soaking now. Will build it tomorrow.
https://www.fasttech.com/p/2345000
Next day...
I've been vaping the Cthulhu alongside the Goblin, same build (3mm 26 ga. 5/6 wraps, cotton), similar juice, equivalent power. As expected, the vape quality is excellent, thus far indistinguishable from the Goblin. Both worked great the first try, no threading, wicking or leaking issues. Cthulhu is a bit easier to build because the deck is a little bigger, though the Allen head grub screws are as always more fiddly than the Phillips pan heads.
With the same build it's possible to get a dry hit with Goblin if you really try or if it has just been topped off. The Cthulhu is harder, and I haven't been able to get one yet. Cthulhu's deeper juice channels keep the wicks saturated extremely well.
Don't let the Goblin's huge external air holes make you think it breathes better. Max airflow in both of these is limited by the build not the base or chimney. There's only so much room left with 3mm coils and short fluffy wicks. With the same build and AFC wide open I can barely tell the difference in airflow between the two. Smaller coils might make a slight difference noticeable however.
That leaves differences in features:
Goblin comes with an extra short tank and chimney. I never use it because of the low capacity but somebody might.
Cthulhu has a proven top fill implementation in addition to the bottom fill screw port. Top fill is important to many, and if I have it I tend to use it, but it's not a crucial consideration.
More important to me is compatibility. Here the Cthulhu shines. Any of the standard 34mm Kayfun/Orchid threaded tanks fit because of the threaded top cap and chimney design. With Goblin you have to add a Kayfun/Orchid standard top cap and a standard Kayfun chimney. The Cthulhu chamber threading is also compatible with Orchid, a big plus for me, while the Goblin chamber threading is compatible with nothing out there.
The Cthulhu is the one I will buy again, over Goblin and Silverplay, both of which I'll continue to use. It's great by itself and an even better as an addition to the compatible parts bin. AFC is not a requirement for me because I vape wide open full time. But you never know when you want that little extra adjustment for taste. Of all the AFC bases among these types of attys, Cthulhu strikes me as the best out of the box. Goblin is very good but smaller with shallower juice channels, and I've had a few issues with Silverplay clones that I won't get into here. I don't have a Billow V2 but imagine that one to be right up there as well.
Orchid still remains my favorite as a basis for modification. No external AFC keeps it smaller and lighter, and the simpler juice channels allow me to modify for JFC without limitation. If I had to pick a second for the purpose of modification, however, it would be Cthulhu.