my experience of the BDI is exactly the opposite of that mentioned above. It has always performed well for me and those i loan it to. (it is held as a spare bass DI as a part of our church's PA.
personally i own both the VXL, bass exciter and the mxr. The mxr it was i will always by choice. an excellent piece of kit. IME far better than the BDDI. I still have a hankering to try the tone hammer though!