I got an OS-6 in trade for a 4-string I didn't need any longer, so I thought I'd fix it up and review it. Here's what I posted on Amazon about the thing:
You'll notice that this banjo has the one-piece metal pot (shell) with the little spikes poking out. In most student banjo lines, that makes it a step up from the resonator banjos with just little screw-on brackets holding the resonator on. It's a step down from most banjos that have tone rings and resonator flanges, but in 6-string banjo lines, you've got to go pretty far up the food chain to get to those. The solid metal pot imitates the volume (if not the tone) of professional banjos. That's why in 5-string lines, it comes between the bracket models and the professional lines. Technically, this is built like the basic Dean B-6. The neck is very similar to Washburn's entry level 6-string banjos, and most of Oscar Schmidt's guitars. A little bulky, almost like a Harmony neck, but still very playable.
UPDATE. I spent several hours with this. Cleaned it up, tightened the head. Adjusted the neck (using an Allen wrench to tighten the neck adjustment rod until I got fret buzz, then loosened it until I didn't). Put on new strings and reset the bridge. Now it sounds great and is fun to play. Not keeping it, because I have two other 6-string banjos already, but I've proven its worth, once it's properly adjusted.
Note, whenever you get a Chinese-built banjo under $1000, you will have to set it up or find someone who can. This is the third student 6-string banjo I have set up, and all played and sounded great after I was done. This makes me think that one of the main reasons 6-string banjos get a bad rap is that so many find their way into amateur's hands without bring remotely ready to play.
Best of luck, and enjoy your music!
Paul Race - Creek Don't Rise