I have that same puller and have used the 14mm recess to remove the crank bolt sometimes, but I never thought to put a 14mm allen wrench in it when pulling the crank. That would give pretty good leverage for most cranks.

In the past year, I've pulled cranks on 2 bikes that probably had the cranks installed back around the Carter administration. I was using a 15" adjustable wrench to crank on the puller. I was a little beyond where I thought I was going to strip the crank threads out and the cranks hadn't budged.

I stopped and sprayed PB Blaster on the crank, tightened up on the puller as much as I dared, and banged on the crank with a dead blow hammer. I sprayed more Blaster and let it sit like that for a half hour. A few more blows from the hammer and just a tad more torquing on the puller and the cranks came loose.

Waving a luck rabbit's foot may have helped too; I can't say for sure. The leverage was definitely needed, but it seemed like a fine line between pulling the cranks and stripping the threads.