What's the difference between an OD and a booster? I thought all a typical OD did was boost the preamp so that you get a sort of natural distorted sound, where distortion pedals and fuzzes were actually changing the wave form...
Anyway, I really like the subtle Klon sound, and I've gone all-in with the craziness about it all. I think it's great that they're astronomically expensive, so that everybody goes nuts and gets all polarized, and most of all, so that there are so many great Klones out there as an end result.
Anything labeled as an overdrive, fuzz, or distortion creates it's own square wave. The real differences are in the topography, filtering, and maximum amount of distortion available. A Klon is like a Tubescreamer in that they don't have a lot of distortion available, even though the circuit does create some. They're best used with the gain down and the volume up, as you described. So they're overdrives.
A boost usually doesn't have both gain and volume controls. The EHX LPB1 is a prime example of a boost. It can color the tone, but mostly it just drives the amp. DOD just reissued the BiFet Preamp, which is a great boost.
My favorite booster is the ZVex Super Duper. One side, yellow, is just a straight booster. I use it as a line buffer. The other side adds a master volume to the circuit. Even though there is no filtering, I would consider the red side an overdrive, because the gain drives the master into overdrive at the top end of the range. There's no "soft clipping" like a Klon, Timmy, or Tubescreamer though. It's a hard clip. Which, to me, is why it works so well on bass. It's an immediate sound.
The larger problem, however, is that most dirt pedals out there are just a tweak of some early circuit, and aren't labelled as such. So you get 1000 variants of a tubescreamer and no real variety. Especially with all of the snake oil in this market, finding out what something is can be frustrating. This is what makes the Klon discussion irrelevant to me. I don't like soft clip overdrives. I learned my lesson with Tubescreamers and re-learned it with the Soul Food. I like a hard clip that's uncompressed and unfiltered with a relatively tight bottom end. Those are few and far between. So it keeps me from wasting money on overdrives and fuzzes. Allegedly.