I can pop even the tightest 3 foot paper birch and douglas fir with an 8 pound maul. I must have 4 cords of each. And, about 4 cords of lodgepole pine also. I had a splitting axe like yours, richard, but then I upgraded to a big heavy maul and it made splitting easier. If I split for an hour a weekend I can get a few weeks ahead on the wood. If I have a few weeks off, I can get a few months ahead, all at a leisurely pace.
I don't sell wood, so I don't need a splitter. I split it as I need it, or as I find the time (have spare time)
I'm pretty pooped after an hour of swinging the 8 pounder, but it's all about mass. You can have a high tech 3 pound axe, or a blunt stone-age maul and smash wood to bits easier than you can with a lighter tool. It takes more a$$ to swing something heavy, but it splits wood faster and better than something lighter, no matter how pretty or sophisticated the name.