We're taking a really indepth look at FATE. Currently we have decided on a magic system and are just waiting for my copy of FATE core to arrive through the post, as the .pdf version made my eyes bleed.
Ah! So it really is the perfect system for Tropis. You don't even need to play it, just force everyone to read the .pdf version until they pass out from either nervous shock or blood loss.
It looks like a decent enough system and the magic system, linked above, is perfect for how me & Alex imagine Ætherical manipulations to work in our world. How combat resolution works will be the deciding factor as I feel it simply wouldn't be Tropis without my signature combat-based body-horror.
Amusingly enough, your XP and leveling system also involves body horror...
On that note, you may wanna check out this Actual Play summary of a guy using Strands of Fate to run a horror game for his niece and nephew, where they experience such delightful treats as having an ear torn off, a nail ripped free, a tooth knocked out, plus a seeping arm wound.
Apart from the Achtung! Cthulhu RPG itself, people have had their own ideas for running Cthulhu horror RPGs with FATE, as well regular horror RPGs - note the recommendation to check out some of the free downloadable Dresden Files scenarios, such as Night Fears, which is allegedly a rather nice little horror scenario using FATE.