I totally get what you're saying about the L's controls. They definitely are unconventional and take some time to get comfortable with them. My L-2500 is the only bass I have with that level of complexity, but I love it anyway.
That doesn't mean I haven't wondered about a M-2500, though. I have. But, since I have a few other basses with a "conventional" controls layout like the M series, I'm planning on keeping my L. Part of the reason is that it's different enough from my other basses, but part of it simply that it's such a great sounding and versatile bass.
But, like I said, I definitely get your point. If I would have sold my L before I finally connected with it (I considered it at one point but now I'm glad I didn't!), I'm sure I would have tried an M-2500 next.