Dyna-lite 804s?

Hi Folks,

I am considering buying some Dyna-lite 804s through Craigslist and I'm interested in user feedback. These would be my first set of studio strobes so I don't have much experience to go from.

Do the Dyna-lites stack up well against others in the same price range?

Do the 804s have a good track record?

Do they permit ratio changes?

What are the signs for to look out for in terms of abuse or coming failure?

Thanks for your help!