Excerpt from guitarpusher.com
"Which one is better, Elliot Lemi AC or Fishman Isys/Presys pickup?
With guitars and guitar gear, most answer is "it depends". It depends on your sound preference and usage. In our opinion, the Elliot Lemi pickup is great for recording or guitar-vocal performances, while the Fishman Isys/Presys pickups are great in live band setting where the acoustic guitar needs to cut through the band. Piezo pickups have a focused/articulated sound that cuts, while bridgeplate transducers give a more natural / airy sound that blends.
The other consideration is active / passive. Active pickup systems like the Fishman Isys/Presys are powered by battery and employs a pre-amp to shape and amplify the sound before going out of the guitar. This enables many functions like volume and EQ shaping, tuner, feedback control making them more handy in live situations. The Elliot Lemi Acoustic Clear on the other hand is passive. It doesn't have circuitry inside the guitar so volume and EQ have to be controlled to the equipment where it is connected. However, it is handy because you do not need a battery to power it. It is also minimalist.
Choosing between passive transducer or active piezo system will depend on the needs of the musician. To get the best of both worlds, we also offer DUAL PICKUP SYSTEMS employing Elliot Lemi Acoustic Clear and Fishman Isys in one guitar, making it a dual output system. With this setup you can get the best of both worlds. Use the Fishman for live setting and the Elliot Lemi for recording or if the Fishman run out of battery. You can also use it for dual-track recording to blend both signals and get the perfect sound that will work for your material."