Correct on the "disposable".
Things like off-axis response don't make one single difference in my case, as these would be 1 mix for 1 person, usually keyboard player, or backup vocalist/guitar player, etc... SPL and reliablilty are concerns, probably more the SPL than the reliability as I would only be using these a few times a month...not touring.
I guess I'm not sure of the sounding lousy comment. If they have somewhat low distortion can't you just EQ a speaker to sound acceptable? Those $1000+ monitors that use speaker processing and are bi/tri amped sound like crap without the speaker processing(fancy technical words for eq/phase/delay?).
What makes up the sound quality of a particular speaker? Very few speakers come any near having a flat response without any processing, and if two similar speakers have similar low distortion characteristics and similar SPL outputs, won't they sound pretty much the same if they are flattened using smaart or some similar tools?
I've mixed on a lot of crap(some of it my own crap) and Midas Legend 3000s with McCauley Line arrays, and although I may not know as much of the technical stuff as most here do, I have been told I have a pretty good ear, by some pretty picky people. I'm obviously not the one to judge how good my ear is, but I relish criticism as it forces me to learn why something sounds the way it does. It's certainly much easier to make a Midas/McCauley rig sound better than a Yamaha Club series rig with an old Mackie 1604 board, but it's also pretty easy to make that $200,000+ system sound like crap, just louder/cleaner crap.