TAZ 5 firmware 1.x 2.x differences

There are several locations to receive firmware from. When in Cura I can install the latest firmware to 1.1.9.34. On the Lulzbot download page there is 1.1.9.28 linked: http://download.lulzbot.com/Software/Marlin/1.1.9.28/Marlin_TAZ5_SingleExtruder_1.1.9.28_193d1f804.hex

I can see also there is a 2.x firmware available: http://download.lulzbot.com/Software/Marlin/

What is this firmware for? Is it ok to test this with a TAZ 5?

Thanks
Thomas