What are the differences between these two pedals? I've read consistantly great things about the DiscumBOBulator but havn't seen a whole lot about the MXR. I heard someone play one in a store once and it sounded rediculous but I havn't had any experience with one myself. I'd like to get one of these pedals. Also, anyone compare the MXR M-188 to the guitar version with their bass?