Folks, "Turbolight" refers to the lighting optical system in all 3 of these DLP ranges, the 731,732, and 831. Overall they contend the 10% greater light on a given wattage. The 831 has a 180watt Turbolight rather than a 150watt Turbolight so you are not comparing a non-Turbolight to a Turbolight when comparint the 731-32 to the 831.
I am pretty much sold on the 65831. If I am gonna buy this TV and assume a life of 10 years, the extra money amortized over the life seems to me to be worth the higher contrast screen with the brighter light and you know, the extra remote will be usefull when I set the system in "babysitter mode;" she can use that simple remote.