It might be overkill to have both, unless you'll have sources other than the DVD that the TV's chip will improve. That could be possible. For instance, if you have an HDTV receiver that sends raw data to the TV, the Faroudja chip might improve this. See the following for instance:
http://www.av-outlet.com/en-us/dept_335.htmlSame with regular 480i; the Faroudja probably does a good job scaling this and removing artifacts. So, if you have more sources than the DVD player, I'd get the higher quality TV.
Plasmas do have a lifetime, which supposedly is relatively long now. They also are susceptible to burn in (a static image gets "burnt" into the display). However, most TVs have anti-burn-in circuits.
I'm also interested in the Samsung v. Pioneer, as Samsungs are much cheaper.