Try this link as well, it explains 3-2, and compares progressive DVD:
Two good DVD to watch for the 3-2 effect:
1. Super Speedway, Ch. 7 stadium scene, Ch. 21, also stadium
2. Titanic DVD, eveytime Titanic shows up, lots of diagonal lines and movement, this is where 3-2 effect is most easily seen.
If you are trained to see this effect, you can spot it easily on all movies with moving scenes (not quick motion, but panning the camera). Other good DVDs incluse Haunting and Armageddon.
Once you saw the DVD demo, visit the link again, then you'll understand what 3-2 is, and why it is important on big screen.
So, when people judge a scaler inside a projector, there are two things to watch:
1. Video processing, does it have reversed 3-2? does it handle 2-2?
2. Scaling, after progressive processing a 480i to 480p, then the scaling is in to scale the image to fit the panel.
LP350 is said to have a good scaler, becuase it uses Genesis VLX-1A, it's both a reversed 3-2 processing and a scaler, that's why people are impressed with it. But it does not handle 2-2, see the above link, it has a good comparison of Genesis chip to DVDO chip.
Most projectors uses scaler other than VLX-1A, hence they handle movies poorly, that's why an iSan is recommended since it has a good DVDO chip, but iScan just process the signal to 480p, it's the projector's internal scaler to scale up to, say, XGA panel. The scaling can have artifacts, even fed by a perfect 480p signal from iScan.
So, you might ask, what's the best projector? Well, I havn't seen one yet, the ideal one maybe using a DVDO chip, and feed the 480p signal in digital form directly into a good scaler. When people uses HTPC, the signal is extracted from the DVD in its progressive form 480p, then use the super high end graphic scaler like GeForce 256 to scale it, still in digital domain, to the projector native resolution. NOW, that's the best existing solution, and that's why many people of this forum is using HTPC.