I've been using a BB for a couple of months now and like it a lot. Its similar to the sound of a good tube screamer but without the mid range hump/honk and is also more transparent- doesn't really colour yoir tone- just gives you more/intensifies of what you've already got.
Works well with all my amps (nano, JMP, Corn Harly) but its particularly good with the Harly as it doesn't add any more mids. If you're into 'low distortion'
singing leads then worth trying one out- but very different in tone to the SD-1.