the major problem is the iso lock to 400
i can't get rid of it in any mode either AV or M
and the worse thing, even when i don't use the flash in e-ttl
somehow the camera locks the iso 400 if a flash unit is connected over it.. doesn't matter the other settings..
if you want to take wide angle shots based in high iso the subject is lit in front from the flashgun and the background goes black with that stupid iso400.
A continuous led light insted of flash probably would save a lot of trouble but even then you'll have to play with the amount of light, (tune up for portraits and tele shooting, tune down when using wide angle)
pffff i got stressed