Flying with SLA batteries? You may need proper documentation in order to get the batts on the flight.
I strongly recommend carrying on your batteries. If you carry them on and there are security concerns, it's easy to break out the documentation - a brief delay and you're on your way. If you pack the batteries in a checked bag and there are security concerns, the bag will not make it to your final destination.
See the Reference (http://www.taperssection.com/reference/) section for the Panasonic MSDS PDF (http://www.taperssection.com/reference/pdf/Travel_PanasonicSLA.pdf).