I tried using sraw and didn't make a difference as far as # of frames recorded.
Very strange. Are you really sure that you've set the 'Pic Quality' to 'SRAW' (Without anything else) and then rebooted your camera?
If you don't reboot it, 'SRAW' doesnt work. Maybe you forgot that?
It makes a huge difference in terms of how many frames you can get, if you use 'SRAW' since it increases the shoot_malloc buffer by 30 Megabytes. And it is the only real benefit of using a Tragic Lantern 2.0 build instead of the normal Nightly Build version.
With the 'Pic Quality' set to 'RAW' I get between 180 and 240 frames at 1280 X 544 (2.35:1) 24p and with it set to 'SRAW' I get 270 to 330 frames. I would call that a difference, so I guess you made a mistake somewhere

Another tip for slightly increasing the amount of frames: Set the resolution in the Canon menu to 640 instead of 1920.
That reduces the size of the YUV buffer a bit and leaves more space for Magic Lantern stuff. But it helps only a little bit.
Using 'SRAW' is the most important setting for "long" recordings at higher resolutions.
By the way, why are you using ISO 1250? What does that have to do with the performence?