I agree with you about using dewormers when you need to and not as a matter of course, for what it's worth.That's really good to know I'm really thinking about investing in a centrifuge. I'm someone who believes you should only worm when you see a problem, some people think that this is ridiculous.
I have heard that excessive use of wormers and antibiotics makes the parasites and such immune which isn't good. I heard this from a veterinarian and I've always held that in my mind whenever someone tells me I need to worm my chickens twice a year or what not.
I am a parasitologist by trade, and can help with getting yourself set up and oriented to do your own fecals if you need it (same goes for anyone here).