Again, thank you all for the input here.
In case any of you are lying awake at night thinking, "gee, I wonder if that guy bought the 500 ps?" Well, we got our HP230 fixed. (It's amazing how quiet it runs now after having it serviced after 6 years of continuous and trouble free use.) We are going to save our pennies and go for the 800 in a few months. The idea that it crunches the plot files on the plotter rather than at the machine is the biggest plus that I can see. Besides, when you add to the base price of a 500 ps the ethernet card, the HPGL2 card, the 42" wide capability...the 800 really doesn't cost that much more. I have come to realize that whatever digital equipment we purchase...computers, scanner, whatever...we always end up using it to its full potential rather immediately. So my theory here is that if I want to output a color D size perspective, the 800 will have a greater chance of getting the job done without a lot of fuss.
I am also beginning to pride myself (the IT guy, who just like the ad, is the HR guy, the trash guy...in short, the owner) that we can go for a week or two without any system hangs, errors, or crashes on any of our 5 machines. So the stability of something like the 800, or let me put it this way, my perception of the stability of the 800 vs the 500, is also a strong factor in making our decision.
But then again, this HP 230 will probably give us another 6 years of trouble free service!