Well, all arts are the same. Formatter, bulb, chip, power supply, ballast, the only difference seems to be the motherboard.
Methinks that Mitsubishi added the dark detailer to the board and changed the light engine model because of it. I highly doubt it requires a different lens or color wheel to project what is coming off the chip.
After all, i did hear someone here upgrading their 733 to a 734. I don't think I should have any problems. Hell, it's $50 on cl, worth it just as a hobbiest.
If anything, i can just trade out parts on the 833 until it works