I think it depends on your usage scenario and personal preference in sound "type"
The micro BL has very powerful amp, better than a lot of desktop mains powered amps in fact, BUT most of that power comes from the inner battery (it uses a mix of USB power and battery to achieve it) so even if you use it as a desktop unit you have all that battery management stuff, which I personally find a bit annoying.
Wish they had put an optional power input to switch to when stationary (maybe powered by their own ipower wall wart).
DAC wise, the chip IFI likes to use is technically inferior for sure. They use it because it sounds very "analog". They say its distortion profile is similar to tubes distortion.
I am personally using the nano BL right now, which has the same dac chip as the micro, and I can conferm it does sound very lush and analog.
However from what I can hear it is not the cleanest or the most resolving dac out there.
iFi guys are very good at implementing it though, minimizing jitter, power and ground noise, etc.