We certainly all have our opinions. A few things are certain--
While the 250 is, most definitely the rarest, in a buck from tradition this rarity has never translated into pricing premiums. Why? I don't know, but can suggest that the cars are really very similar as far as the market is concerned. Our collective vast knowledge here exaggerates the differences; the market never has.
The 280 is generally, by price at least, the most desired.
I would agree that the Pagodas are single, not dual exhaust. Two tips on one muffler doth not make a dual exhaust. With mufflers and resonators shared, most woud call it a single exhaust system even with two pipes.
There really are very few "emissions related" encumbrances that affect this car; what does can be bypassed or removed easily on the late-model units. That's a testiment to quality engineering. I think I removed the one wire from one solenoid on mine...no difference in runnability.
Just another article to add to our collections!