Those Hitachi Plasma's are NOT Interlaced! No such thing as a Interlaced Plasma or LCD. Nothing new about a Plasma or LCD being able to use a 1080i INPUT. Big deal, it's still De-Interlaced and scaled down, also according to CNET that Hitachi P50H401 got a 2 1/2 out of 5 star rating. If you think the picture looks amazing, you have low standards. Reading the review, it didn't sound all that great to me. Yours is also scaled down as it's not a true 1080P display, other 1080P displays just de-interlace the 1080i signal. It's a odd ball so called 1080P display. There's always a few of them out there, generally though a 720P plasma is 768P.
Plasma and LCD's by Design show a Progressive Picture. Interlaced is how TUBE TV's show a picture. Front Projection, Rear Projection, Direct View, TUBE. Plasma's and LCD's just don't work that way. They will take whatever INPUT you give it and process however way it needs to be to be displayed at it's Native Resolution. Period. There's not a single Interlaced Plasma or LCD out there.
Part of problem is a few places advertising 1080i Plasma's. Look as the Resolution and it's not 1080i, it's 768P. This is confusing a few people out there. You can't set your PS3 for example to 768P, it's either 720P or 1080i. Since in theory it's better to scale down and loose Detail then to scale up and add what's not there. Seeing any Improvement setting at 1080i is pretty slim. It.s B.S. Marketing. Any HDTV out there will allow just about any INPUT, 480i, 480P, 720P, 1080i and 1080P and De-Interlace, or Interlace, and Scale up or down to whatever that Displays Native Resolution is. A Plasma and LCD just doesn't display a picture the way a TUBE TV does.