I think SLA will be around for quite some time at FRC due to its track record. I've been to one event in my entire FIRST existence where a venue was evacuated due to a battery spill (2014 Greater Pittsburgh Regional). I don't know much about the variations in LiFePO4 manufacturing, but I imagine this would weigh highly on it being allowed in the future.
Nuclear fission is safe. Can I use that?
LiFePO4 see some extensive use at the
University Rover Challenge. Check it out if you want to be part of a growing, challenging competition at a university level!