I use the Zoom A1X Four for chromatic harmonica. I love that there are presets for violin, trumpet, saxophone, harmonica and more respecting the timbre of the instrument.
The preamp easily connects to an XLR (mic cable).
I mainly use the delay and program the level or feedback to the expression pedal. I play jazz but also a lot of reggae shows for which the tape delay is an awesome effect. The octaver and chorus is also a nice feature.
For blues harp it has a bullet mic simulator to get that typical crunch.
For the price and range of effects there are no disadvantages to this pedal.