Not trying to talk you out of it, just give it some thought and you may be better off buying the wood cut split and delivered.
Ja, if you are buying most of your wood like I am, the option of buying it already cut/split/seasoned certainly could be a factor. In some regions, the price spread between C&S and logs is so small that it isn't worth the expense and mess in the yard to DIY.
When going with more tonnage, look at the specs of the pump. Tonnage is had by using a larger cylinder and a larger cylinder needs more GPM and larger motor to keep up the cycle time. More tons with fast cycle time means more cost. Since most of my wood splits real easy, cycle time is a big factor for me hence my short-stroke mod I linked to.
Four-way wedges work best on splitters with a fixed wedge and H/V convertible splitters don't have fixed wedges. On moving wedges, the horizontal wedge tends to drive some of the splits toward the beam and puts a sideways force on the sliding wedge. Four-ways also work best with a particular diameter log unless you get into the fancy models where you can raise/lower the wedge. With some of the larger rounds I split, a four-way would leave many splits too large and would require resplitting. With smaller rounds, it would split off centre and tend to chip off wedge-shaped pieces.
Fixed wedge splitters should have an out-feed table so you don't have to pick the oversized splits up off the ground to resplit. Even at that, you have to reach farther to bring the splits back to the beam since they are pushed away from your operating position. If you split a lot of small stuff, the fixed wedge is nice cuz you don't need to toss the splits out of your way. The ram will push the pile and you can move the splitter forward. My neighbor keeps his hitched to the tractor left in neutral and the ram rolls the tractor forward as the pile builds up. I have the moving wedge and need to toss the splits.