I found the Fiskars 8lb iso-core maul for a reasonable price locally and had to take a gamble on it.
HOLY HELL I wish I had known of and purchased this sooner!!!
While the X27 is still the main weapon, the iso-core maul was busting stuff up in 1-2 strikes that the axe wouldn't budge in 4-6 swings. On my trial run, switching back and forth, in large, knotty but relatively fresh tan oak that had been sitting for several weeks bucked-up, I found the hardest part was not letting the maul sink all the way to the bottom into the dirt. The shape of the handle is different, and it changes how my hands wanted to work it from release to post-impact. In time, I'll adjust.
I'm very impressed with this tool.
Photo was mid-day of a 5-6 hour splitting day. The other two trunks had been split (mostly) prior
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This was a couple weeks before:
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