Samyang 24 f/1.4 vs Canon EF 24 f/2.8 IS USM? What would you choose?

[Dr Croubie]

Now here's a random question, to distract us all from that dastardly D800 thingy going on...

Given that we know little to nothing about the IQ of these two (samyang samples have been released, but not reviewed properly yet), but we do know the rest of the specs (especially the price), which would you choose?

Samyang 24mm f/1.4, €600, fastest-in-length aperture, no AF, no IS, 97mm long, 77mm filter, (i haven't seen a weight but their 35mm is ~700g).
Canon EF 24 f/2.8 IS USM, €800, slow aperture (for a non-macro-prime), USM AF, IS, no specs on size but i'm guessing halfway between 50/1.8 and 85/1.8, so say 350g and 70mm long, probably 58mm filter (maybe 62 at a pinch).

Based on how good the IQ of the samyang 35 is, the 24/1.4 probably won't be quite as good, but still should be very nice.
And given how slow the canon is, and all the fancy elements it uses, it should also be a lot better than the current canon-offerings.
Build quality of both should be about medium, not the best L-standard but nowhere near 50/1.8 or kit-zoom flimsiness.

So, if we take it that both have roughly the same IQ at the same apertures, the samyang goes to f/1.4, the canon has IS and USM, the samyang is bigger and heavier, but 25% cheaper, which would you choose and why?
(assuming you'd buy either, lets just say you're forced to buy one or the other, I know many people would like option C or neither...)

[Kayaker72]

Hi Doc,

Some of the specs for the Canon are out there (canon USA's website). You are correct in that the lens will take a 58 mm filter, and it is 2.69x2.19 inches and 9.9 oz or 68.4x55.7 mm and 280 g.

Ok, so I am forced to buy one and am assuming IQ is equal, then the AF on the Canon would be worth the extra 200 too me. The Samyang allows in more light (granted:http://community.the-digital-picture...t=f-stop+blues), but, without AF, I don't see it as better at "stopping motion" (and the whole f/2 issue). The 4 stop IS from Canon actually gives it a 2-3 stop advantage for hand held, low light shots. I'd think about DOF a little, but it isn't like we are talking about razor thin DOF at 24 mm. But ultimately, this would be about having AF for most normal shooting conditions.