I borrowed a friend's years ago, base model with table added. It worked great and split most anything offered to it.
Eventually I ordered my own and decided on the HD because I intended to keep and use it for years and years and the price difference seemed small enough to just go for the top of the line model. Still no regrets about that.
Actually ordered mine without an engine and mounted a used Kubota diesel I already had, that too has been great. I like the low engine mount much better than the high, a little more stable though I haven't tipped mine or the original design over. Only regret about the engine conversion is the $ I saved buying it without an engine wasn't very much, pretty sure I could have sold the new engine locally and come out further ahead.
The Super Splitter will split about anything and cut through most of those that won't split. Occasionally though you'll find a piece full of knots or otherwise more difficult to deal with than it's worth, but not very often.
To keep the splitter busy with no down time takes about 4 people. One running the chain saw, one on the splitter, one helping feed splitter, and one or two stacking if you're not just making a pile where they fall. Adds up to a whole lot of split wood in a day. Obviously you can run it with one person, but the point is the splitter won't be the slow point as with the typical hydraulic splitters.
Only negative qualities is the thing is difficult to transport. Even if you don't intend to take it anywhere chances are you will at some point if you have friends who burn firewood. Hard to load in the back of a truck safely and they lack good tie down points. If you had a low trailer with a wide ramp like for lawn mowers that helps. Otherwise I use forklift and slings to load it in the back of a truck. Also welded on some rings under the table to help with strapping it down.