convert - Converting las files from version 1.2 to 1.3

I have lidar data set which initial waveform data is in LAS 1.3. The classified point cloud needs to be delivered in the same version, but my processing software (TerraSolid V15) allows me to write point cloud only in LAS 1.2.

I am afraid processing LAS 1.3 to LAS 1.2 may lose the information of returns greater than 5 (possible returns 6 and 7). Will this make any big difference in the final output? And is there any software/tool that can save LAS 1.2 to LAS 1.3.

It may sound silly, but will it make sense processing LAS 1.3 in LAS 1.2 and then change it back to 1.3 again?