Not a review, just an impression
I was flipping through Fate Accelerated at the game store yesterday, and it seemed like the mirror-universe version of my own SFX! There are strong similarities (maybe because I played and hacked so much FUDGE back in the day), but almost every concrete difference I noticed was the exact opposite of how I like things to be. Starting from the very beginning with the description of the purpose of this tabletop RPG being to gather around with your friends to take turns telling little parts of stories, through the FUDGE special dice, the use of names that need to be continually converted to numbers and back, and the damnable economy of points that need to be spent to actually have the fiction of the world have any bite, the meta decision whether to have a failure or a success at cost, negotiating back and forth over “compels”… I can practically feel the game staring at me, stroking its goatee and toying with its agonizer.
Anyway, you can currently get the pdf (or epub or mobi) version as Pay What You Want over on RPGNow. If you ever wanted a game that has many of the elements I like (rules light, freeform chargen, resolution driven by genre-logic, shared responsibility for the details of the world) delivered in a way that makes me cringe, check it out.
http://www.evilhat.com/home/fae/
Tales of the Rambling Bumblers 
So, as someone unfamiliar with your SFX! system I ask… what does it do? How would you sell it to someone who is familiar (and likes) FATE, beyond saying it doesn’t do X? That may come off not exactly how I intend, but I can’t come up with a better way to ask… so know that I’m being sincerely curious. Curious enough to probably go DL one of the implementations you made to look at, but I’d like to hear in your own words…
So SFX! is a rules-light(ish) system that uses largely free-form character generation, with players describing what their abilities are and how they operate within certain constraints on how effective the abilities are relative to each other and in absolute terms (based on the scope of the characters), which allows the players a good deal of say in coming up with the exact details of the environment as they go, and focuses on resolving actions according to the logic of the genre but allows for and encourages players sticking to a strictly in-character stance and avoids meta considerations such as story and dramatic structure as much as possible. The goal is to role-play and imagine your character in a world where such stunts as swinging from a chandelier when fighting, or jumping your motorcycle over other cars (depending on genre and tone) are plausible without actively trying to construct a story about that world, and without either trying to assign a probability for every little thing or negotiate it with the GM, or forcing you to reason from story considerations (obviously I can make this jump because I’m the protagonist and the story can’t end here). SFX! allows the players pretty much unlimited opportunity to interact with the fictional details of the scene and attempt to use them to their advantage, while constrained by the mechanics as to exactly how successful that turns out to be.
Does that help? I could talk about specific ways that FATE Accelerated does things vs. SFX! for the equivalent situation, but that’s probably more detail than you really care about.
Heh, don’t be so sure.. I am interested in detail. But thanks for the summary… it helps somewhat but I’ll probably just have to do a read through to get a firmer grasp on what you mean. It looks interesting, at the least.
The biggest mechanical difference is that FATE Accel throttles your opportunities to interact with the fictional world with the use of meta-gaming points. In SFX! if an opponent is buried under rubble, he’s either Hindered or Out, depending on how badly buried he is (which depends on how whatever buried him scored vs. his defense when attempting to bury him). He has to deal with the consequences of the fiction whenever it’s logical; in FATE-A he only has to deal with them if you choose to expend one of your precious supply of opportunities to make the fiction relevant.
On the flip side, if something about your character (probably a Complication in SFX! terms) is going to present a problem for you in the situation you find yourself in, it’s usually entirely up to you to role-play that or to decide that under the circumstances you can’t employ the ability you want because that’s not how you conceive of it. There’s no consideration asked or given for well, should I accept this now because I need the Fate points or is this too important? Nor is there any back-and-forth out-of-character negotiation.