According to the information given in the data sheet of www.cartft.com/catalog/il/1102 this transflective sunlight readable screen has (only) 400 NITS, while it is generally acknowledged that a sunlight readable screen should have at least between 800 and 1000 NITS.
Is there an error in the data sheet (since 400 NITS is really low)?
With transmissive technology you really would need 1000nits and more to "fight" against the sunlight (here the idea is to be brighter as the sun - difficult).
With transflective technology the sunlight itself is reflected in the panel and used as brightness for the panel (the sun helps to make it readable).
PS : You can find real life pictures from Death Valley (US) here :
http://www.cartft.com/community/Story/death_valley