I bought the Jupiter 9 to hold me until I could afford the 77 ltd.
IMHO, image quality is 95% of the 77. Bokah is wonderfull smooth. It can be dangerous sharp. It can be soft wide open. The lens needs to be used with a hood. I use the hood from a Tak 150.
It is a true mechanical lens. Heavy to focus, preset aperture. But it works really well with AV mode. The aperture is continuosly variable. Kinda neat. It smells like an AK47.
It is one of my favorite lenses. When I eventually get the 77, I expect I will keep the Jupiter.
As for comparison to the Helios. The bokah of the Helios is so distinctive, to me comparing it to the Jupiter, is like comparing a fisheye to a rectiliniar. They are two different beasts. Both good, just different.
I bought it from a dealer on ebay. It came complete with the original box, the plastic case and the Russian instruction manual. As with all things ebay, luck is involved.
If you have the cash, I say get the lens.
Eric.