One way would be to take a random 10 blocks about the same diameter and species, mark them in quarters, give 5 to each splitter and first one finished wins.
I was never a fan of the Fiskars myself, until I found myself with nothing. I went out on a limb and tried it because the only alternative was a chinese made single bit or chinese made maul and I wouldn't give a peso for one of those, much less a dollar I worked for.
The real proof came at the end of my first day splitting and my shoulders weren't killing me. The thing is light ,fast, and shaped to split. I'm sold.
I will be happy when I get my Speeco back, but until then, I'll use the Fiskars.