Does horizontal or vertical. I just prefer horizontal, so the big stuff we set on with a bobcat. Splits well either way. As far as i know.... there is no four way available, but it shouldn't be much of a challenge for a fab shop to make one if you want one. I would have one made similar to the timberwolfs that just slips over the wedge, so it would be eaisly removeable. 90% of the wood i want in fours i can do in less than a stroke anyway. Start your split, back the wedge out of the wood, flip the piece end for end and rotate it 90 degrees at the same time. Drive the wedge back in... pop, its in four pieces. Faster and easier than it sounds. I imagine i would have a four way made for mine.... if the size of my firewood were consistant. Being a scroungs and a beggar often leaves me with the big suff others don't feel like working with.
There is often a debate over whether wedge-on-ram (dictated by horizontal or vertical capability) or wedge-on-beam (like the Timberwolfs) is better. I see no benefit to having the wedge on the end of the beam UNLESS you are splitting onto a conveyor. Otherwise i prefer to keep the piece of wood in front of me. I think in my old pictures i had a "shelf" on the far side of the splitter made of half inch plywood as a test. It worked so well i made one in steel this year. I should take a picture. Its great for making multiple splits on the same piece of wood.... keeps you from having to keep picking up the piece that splits away from you. Back saver for sure.
One thing i will recommend to you. Always try to see the splitters you are considering... stand at them, try them if possible. You will want to buy a splitter that is comfortable to work at. I used to work for a farmer who also sold firewood. He had an old mechanical splitter.... i think it was a "jiffy splitter" or something like that. Is sat so low to the ground that my back was killing me after a half hour of splitting..... as i was always hunched over. The beam was maybe as high as my knees. I remedeyd it by putting it up on blocks..... but that gets to be a pain in the rump if you move it around the yard. So.... always try to stand at the operator station on any that you are considering..... make sure its comfortable.
Scott