I've split plenty of wood with a splitting axe, and have a good technique, and a fairly fit so that is viable.
But I have also used my FiL's vertical 7t splitter and it is night and day.
Maybe for a short stint I could manually keep pace in a race between axe and splitter, but I bet I would be give up after half an hour and I would be feeling it in my joints for a week afterwards.
So a splitter is definitely on the cards. I want to batch process a lot of wood in one go, not do little dribs and drabs. No hire option local to me. I would ask to borrow FiL's machine but a) he is very protective of it, and b) it weighs 133kg!
From what I've read, one thing that concerns me is log length- both my stoves are quite small, in particular the 3kW wants logs of 170-220mm, which is far shorter than the maximum that splitters generally can take. Do you have to wait for the ram to fully retract each time, or can you adjust the log length, etc?
I'm hoping that a fairly basic horizontal 6t machine will do the job. I'm going to cut the logs into rounds on the stack, and drop them into a trailer. Then set up the splitter at the same height as the trailer bed, so no lifting required, just sliding/rolling. Then I have a second much lower trailer that I will chuck the split logs into- so again no lifting. Or at least that is the plan!