The 100 amp tester is like getting a cardiac stress test...
"OK all the electrodes are connected. Now grab a book and start reading".
Hospitals have cardiac patients on a TREADMILL not sitting in an easy chair. The 100 amp load tester is near useless. Except if you plan on using a 200 amp hour battery. A perfectly bad battery can pull the wool over the eyes of a 100 amp load tester so fast it'd make your head spin.
The BCI developed the 50% of CCA, 9.6 volts minimum after 15 seconds of loading for a reason.
"I want to test drive your car before I buy it. Say to the end of the block?"
The 500-amp load tester is the way to go. Way to go Bobbo.