$999 for the lens - that does sound crazy. I'll see if I can confirm that from Optoma tomorrow.
As to the better deinterlacing and scaling, the H31 uses Pixelworks. Optoma doesn't say who's circuitry is in the H27. Now, tie that with the question of AI - and here's something to think about - BenQ had a similar situation - they used Pixelworks in the old BenQ PE8700+ (which I have), and went to "we ain't saying" in the PE7700 (turns out its almost certainly Faroudja), and also added AI.
The BenQ 7700 does outperform the older PE8700+.... and the AI certainly enhances dark scenes, etc. compared to the 8700+.
Optoma often trys to keep things a bit murky - especially since the H27 was originally supposed to replace the H31, according to them, but because of the H31's success they decided to keep it in the lineup. They have a different, but equally challenging marketing problem with the H78dc3 and H79.
I found the de-interlacing on the H27 to be excellent. and the scaling was also no problem at all, on 1080i signals.
So enjoy your new H27. -a