[Coler]

Is the sound closer the the mic pickups (faithful / natural) or the piezos (a bit electronic / processed).

I would say very much the former (natural). I use one on my D17 all the time and love it.

You can always just put it in your guitar and run the jack input out the soundhole to see if you like it. I did that and then got the guitar modded to accept the input through the strap button hole once I was happy it was a good solution for me..

I also like how easy it is to take it out if I'm not going to plug in, and replace it.

I often use it with a tech21 acoustic fly rig if not going through my own acoustic amp.