Most on this forum do not respect the BL4.
I bought a pair a few months ago because they looked nice in my bedroom (WAF) and this was more important than their sound. In the store, they sounded horrible. In fact, I almost changed my mind, but decided, what the heck, I could always return them (I was buying a display model). When I first set them up, I was disappointed - they sounded as bad as they did in the store. However, I noticed when I turned them up a bit (louder than I would normally listen in my bedroom), they sounded quite nice. I then took them off their stands and placed each on a sturdy table near a wall, and it sounded much better. I played around with the corner/wall/free switch, and I'm really happy with them. Now that I have them setup, they sound incredibly clear and detailed to my ears. True, the bass is a little lacking, but that goes with any small speaker. I think they would sound pretty good mounted on the wall.
My point is that the BL4 can be a competent speaker. It is true that its bass is compromised by its small size and is greatly influenced by its positioning. It also sounds better turned up a bit rather than very low levels.
Like most, I'd recommend 2nd hand BL4000 vs. new BL4, unless the BL4000s do not fit your room (as was my case). If you really want a small, unconventionally designed speaker, the BL4 is worth a try (just make sure you can return them).
Stan