I'll outline how I use this just in case any other acoustic guitarists are looking for a way to beef up their sound. Works great for me.
If you rig up a sound hole pick up vertically (not the usual horizontal way) the pick up basically only picks up your E and A strings fed into the Sub n Up with the dry and octave up turned off - then mixed with your guitar pick up (I use K&K on my Martin) you can subtly really beef up the acoustic sound with bass. This makes a really big difference to my solo sound.
The Sub n Up tracks extremely well - I also have a POG which tracks the best - however it can sound very - synthetic ... the Sub n Up has a huge bass sound which is more like a double bass sound and dynamically much more lifelike. Be careful you don't over do it if you want a subtle mix.
I've never used the other features as this was bought purely to give my acoustic guitar a better range on the E, A and about 50% of the D string without affecting the treble strings.
Great product for the price and very accurate.