At the moment I am using a 500 Amp load tester and reading the voltage before, during, and after load. Small batteries are difficult to measure this way - even 12ah sizes are too small really, although it works fine for liquid starter batteries.
We have tried that (10 second load testers) and found it seriously lacking in find the true capacity of a EV deep cycle battery which was important for us since the pack of 5 batteries in our 60 volt string can only go as far as the weakest battery, using either a PakTrakr and riding the bike, or, the CBA II and performing a load test, have proven to be the only sure fire ways to make sure the pack is healthy and trouble free.
If someone had a silver bullet 10 second test we would be interested too, but so far, it seems you need to really put a little time and discharge into it if you want to have piece of mind that the pack is in tip tip shape.
Those high amp load testers exists to prove a battery can provide hi amp starting capacity for starter motors, and aren't really the thing to use to determine if a battery has the deep stores for lower amp long time drain capablity.
We took a silicone battery in Sep 2007 that had only 30% of its capacity left, used a starter load tester, the battery passed the test with flying colors, but could only power an EV for 2 miles instead of 23.