Why would you want an XL-ATX case if you're only using SSDs? If you need that much space for a monster GPU array then you'd probably need to remove the drive cages anyway. Or if you're throwing enough cash at SSDs to warrant an XL-ATX case, then a couple extra quid for dual 2.5" adapters won't break the bank.
Just a bit confused by what you're doing tbh.
Have you considered a Corsair 750D or 730T or 780T? All of these will do what you want.
I have the 750D and have removed the cages and it works a treat, best case I have ever owned!
Why not simply use adapters to fit 2 SSDs into each 3.5" slot? That way you can fit twice as many SSDs as there are 3.5" bays.
http://www.overclockers.co.uk/showproduct.php?prodid=CM-019-AK
If you're interested in airflow to GPUs, why not try something like the RV03 - I've got all my SSDs and HDDs behind the motherboard trays and have only a single blu-ray drive in the front slots so there's loads of room in the front for airflow.
Minor point but you are referring to SATA drives as mechanical 3.5" drives I think. You realise that SSD's are SATA drives too, the SATA term is the connecting interface, not a 3.5" format.
SSDs are SATA
2.5" HDDs are SATA
3.5" HDD's are SATA
the Antec 1900 is ideal
Antec 1900 seems a nice case, was thinking about the Corsair 750d, but might have to change my mind now.
Nice case, but I guess what I am saying is, why are not manufacturers designing with SSDs in mind.
Here is a NZXT H630 case which looks really nice. It has two fittings for SSDs at the back of the MB....
http://www.overclockers.co.uk/showproduct.php?prodid=ca-125-nx
But if you remove the HD Cages here....
You are left with a space which would be great if it was also filled with SSD fittings. This would make for a better airflow system for all those GPU's
.
Seriously mate, watch some of the reviews on the 1900 it is an awful case.
The TTL one on youtube is a really good in depth version and the 1900 is full of flaws, the 750D is a much better case.
Sorry I am not quite sure what your issue is, all of those cases I showed you have provisions for SSD's as shown in the picture below. There are 4 x SSD slots that run vertically up the side of the case towards the 5.25" bays.
Have you considered a Corsair 750D