Mr M wrote:
Yes, these can make quite an improvement.
Yes. They also make one specifically for the nylon string guitar. But it's modelling only, so if you want other FX for your (lots of) money. Yer screwed.
For alot less money you could also check out the Korg AX3A Acoustic Effects Processor.
I've looked into those and was intrigued. But haven't got around to checking one out yet. I'm primarily looking for something that can work on an electric's piezo bridge on the odd occasion I want it to sound more like a real acoustic. The Boss AD series and the sim in their GT-PRO didn't work very well at all, IMO.
The only other thing to try would be the D-Tar Mama Bear, which looks very good. Still modelling only, but it does something that the Fishman doesn't - it lets you turn your electic acoustic into any number of acoustic guitar styles.