On my splitter, the wedges interchange. There is a pin that pushes into the wedge that holds it onto a piece of steel that sticks up out of the frame of the splitter. You will easily be able to see it, it is about 1" diameter, just push it out and lift the wedge off the machine, replace with 4- way. I am not sure if the 230 come equipped with this quick-change, or it is an option. Check with split fire.
Split fire recommends splitting tough logs on the 2-way. I have never used my 2-way wedge, 4-way will cut anything, no stalls. Even knotty elm and beech, I've split 30"+ blocks this way, also.
One direction is rated higher, although I do not remember which. I honestly have never stalled it either way. Mine has a 4.5" cylinder, I think the 230 may be a 4", not sure.
Be careful letting young people run this machine. It is different than other splitters in that it will split coming back towards the operator. If someone lets the front block become a hand rest, they will soon have 1 less hand. I let my daughter run the lever as well since she did on all other splitters. I spotted her hand there before it was a problem. She now watches from the swingset. Even had adults want to rest thier hand there while operating....please keep an eye on it.
If you have a quick-tach bucket, set it next to your wood, back the splitter between the bucket and woodpile, stack wood off the splitter in the bucket. This will really save your time. I'll try to have my wife attach a picture of our operation soon.