I have also slowly been replacing fluorescent fixtures with LED tubes. Some rewires, some not. The worst rewire is a snap. Know a few people with whole fab shops doing the same. Everyone loves them. SO much brighter, no flickering, no replacement cycle worth mentioning, and the power consumption is so much lower you'll notice it. IME, high-draw tools (hammer drills, welders) could make fluorescent fixtures dim or flicker but none of that with the LEDs.
Check color when buying. You may think some are a bit too blue, yellow, etc. so think what colors work best for you, or if color matters for what you do in the shop. Yeah, it'll take a minute to understand color temperature, but worth it in the research time.
If doing the very long tubes, note that the LED replacements are not as rigid as glass. They can droop a bit. See how they fit your fixtures, and think of worst cases (got a big door where breezes come in?) and maybe secure the middle. Many come with foam tapes but that seems halfassed, so if needed, more like drill a couple small holes, wire tie them down.
