I would have to agree with your Bluetooth assessment as mine has been outstanding with my Bluetooth 5 device. Haven't had any drop in signal myself except for when I cover the right or left bud with my hand for a few seconds. I can even go downstairs and it takes about 10 seconds for the first dropout. Now for the hissing, it is always there for me when the earplugs are at minimum volume and I have to increase the volume to cover it up.
I have tested the Lag in video on the Liberty plus. I use the Kodi application to watch youtube videos as it allows you to correct for audio lag for each video and the offset is less than 1/4 second in all tests that I have done. My standard wired earbuds have a .1 offset themselves with streaming media.