If you do more with the Amiga than play some games occasionally you just have to get OS3.9 (couldn`t imagine there was one serious user today without it).
BoingBag 1 is a must as it adds multitasking to the WB (so formating a floppy or copy operations that take some time do not block your WB anymore).
BoingBag 2 is a different story, there wher more users reporting problems then the actual benefits were worth it.
You can try it, but I recommend makeing a backup before installing BB2.