I have the WO 10:1 focuser. Smooth as silk. Best photography investment I have bought for the ED80 after the WO 0.8 FR.
I looked at a couple of others that were less expensive and found that there was a slight amount of play in the fine adjustment knob. The WO has none at all and is very direct. I also found that the focuser is slightly shorter than the original Orion one so you may need a small extension tube or a FR to reach focus. This may also be the case for other 10:1 focusers. I find when I'm using the 300D and the Orion Prime Focus adapter I need to leave the adapter out about 5 mm or so to ensure I get enough out focus. It isn't an issue but you should be aware of it. Longer profile adapters may not need this.