IMHO the only reason to choose LCD over plasma as a technology is light reflection and in your case that is not a problem.
Likewise, the only reason to choose 1080p over 768p native resolution is viewing distance. If you plan to view the display at closer than 8', then 1080p is a necessity otherwise you will be hard pressed to see a difference because your eyes will not be able to resolve the additional resolution and SDE should not be apparent. Your eye's distances may be a little different but not by much.
So unless you cannot control light reflection or need to sit very close, get the plasma. The picture is fundamentally better. Again just my opinion. Let your eyes be the judge but do it in an environment similar to your home not a bright store.
BTW The Pioneer 5070 is a good display. The Pioneer Elite is much better but a good deal more expensive. The Pioneer 507cmx, their comercial display, with a KeyDigital card for processing and connections is as good or better than the Elite and now actually costs a bit less than the 5070. Nobody should buy the 5070 let alone an Elite until they have considered the 507cmx alternative. It looks good too in a simple dark matte finish unless you are so sold on the shinny black of the consumer line.
Contact Chris at Cleveland plasma for details. That is where I found out about the cmx series.
Cheers,

Gary