I've owned a Micro BR for a couple weeks so far. I've only done a couple things with it so far so I'll stick with what I know.
I've used the time stretching feature to slow down mp3 files for practice purposes. The resulting slowed-down file isn't as smooth sounding as the time stretching that occurs on my Tascam Bass Trainer. But, my Tascam is finicky when changing amounts of slow downish-ness then going back to regular speed to the point where I end up restarting the song. This isn't bad when I have plenty of time but I'm usually practicing in the 45 minutes left of my lunch after cramming food down my throat so this finickiness becomes an issue. I don't have the finicky problem with the Boss.
As far as the drum machine goes, I've only messed with the metronome track. It makes a different sound on the one. Some people are OK with that and some aren't. I've heard there's a workaround to get all clicks sounding the same but I haven't tried it or gone looking for the workaround so I can't comment on that.
For recording purposes it was pretty easy to set up. So far I've only used the built-in mic for recording. If you're interested I can post a clip. I just put the Boss on the other end of the cellar we practice in and let it rip. I tweeked the mic sensitivity setting so clipping wouldn't occur. Clipping sounds SS bad when it occurs so you don't want that to happen. Let your bandmembers band away at stuff and adjust input gain & sensitivity while they do that. Obviously if you have a board/mixer you can use that.
As far as multitracking goes, the most you can record is two tracks at a time. This can be both off the mic, both on the stereo line-in or guitar in & built-in mic. If you use the instrument/mic combo though, both are dumped to the same track according to the manual. I haven't tried this personally, just quoting from the manual on this one.
I was able to fit 3+ hours on a single 1GB sd card. The Micro BR will only work with up to 1GB per card, so don't buy any 2GB + cards as only the first 1GB will be used.
When recording my own practices (not the band, myself) I found one thing that will be a pain if you don't write it down. The tempo for each song resets every time you power down the BR. This means the drum track you selected will go back to its default bpm when you restart your BR. So if you load a drum track and change the tempo from 120 to 86 for example, you'll want to note that because it'll reset to 120 bpm. I thought I was going nuts until I read that this is a known issue. Now I add bpm into the song title.
I didn't find it too tough to work with, but I did carry the manual with me the first few times I used it. I messed with it a few times before I did anything serious with it so I'd be familiar with its operation before I needed it to just work. Now it's a snap to create a new song, give it a title, assign the input to a track and get it ready to record.
One last thing. You'll want to get the power adapter. The BR only lasts a few hours on batteries. I use rechargeable batteries and I'm down to 1/2 strength after 2 to 2.5 hours of recording.
Anyway, if I haven't scared you away, let me know any specific questions you have and I'll be sure to try & answer them.
