I got the Nano Soul Preacher a couple of weeks ago but I really haven't had a chance to do more than just goof with it a bit for a few minutes.
I didn't notice it coloring the tone, but I was at a low volume. I liked the attack switch. At "fast" it was squish from the get go, right on top of it. On "slow" it creeps up on you in an "Oh, there it is" kind of way. Kind of fun.
I plan to put it on my board this weekend and give it a real test.