So after a few hours playing around with A1ex's second release of the 1.1.3 firmware, here's what I'm getting with 14bit lossless option:
 
	3520 x 1320 = max. 1314 frames - ISO within 200-400 range - scales up to UHD with no perceived loss of quality
 
	4096 x 1862 = max. 507 frames @ 12.5 fps - Not sure how useful this would be for landscape work or slow shots. Again ISO within 200-400 range.
 
	Previews: At the moment, not fantastic but definitely better than a black screen. I was able to rack focus with a moderate degree of success.
 
	Camera crashes persistently when using 50/60p modes.
 
	I'm using Komputerbay cards 64GB 1066x
 
	Will try to post a few frames soon. IQ, even shooting at home with crap light, is just beyond words.