I have a USA M-2000 and L-2000. The M-2000 has a hotter output than the L-2000, at least mine does. If the L-2000 is in series and active, it's similar to the M-2000 naturally. The output gain of the M-2000 isn't tamer, maybe the tone is somewhat.
The M-2000 will more easily distort when recording, maybe it's the equipment I have, I have a Motu M4 interface.
I prefer the L-2000 in passive, parallel or SCM for recording but I can get a good recording with the M-2000 but it's a work around the really high signal output and massive bass response it seems to have.
Live through an amp or playing with a band both basses sound great and no issues, I'm not sure about pedals as I don't use any.
I don't find the pickup blend very useful on the M-2000, with mine a little turn off the center detent and it pretty much sounds like the pickup it's turned towards, it's not a very slow blend taper. I run both basses with both pickups on anyways.
If I had to choose one or the other I'd probably go for the L-2000 because with the SCM option, it has a lot of different sounds available.
But I'm not getting rid of either!
The solution is, get both LOL. Good luck!