Does a 2 pole gfci circuit breaker compare the two ungrounded conductors ampacities like a single pole compares the hot and neutral? I am wondering if I can use it on a masonry saw that does not utilize a neutral conductor and still be protected. Thanks

It compares the 2 hots if it is a 240 GFCI and compares a three wires if it is a 120/240 GFCI. Either one will provide protection for a 240 volt saw.
Don(resqcapt19)