Transfreflective screens with backlights will always be what the backlight output is ABOVE the light hitting the screen (allowing for losses of course).
I have seen 300nit trans. screens so they are always 300nit above the ambient but they were £500+vat (about $1000). You dont want/need a 400nit trans. screen, only about 250-300 or even less may be useable in some applications as it would be too bright at night.
Trans. is good and very clever and has been used on character LCDs for years which would be the easiest way for people so see how good they perform