I was a guy going the "without" route but have had success going the "with" universal sonar for the last 5 years or so. I went from busting a transducer or two every year, carrying a spare and changing transducers out on the water to never having a problem.
I did experiment with the extra equipment that you can mount on your TM to protect the transducers but had mixed results with that - especially fishing grass. I prefer a clean with nothing attached to the motor.
Regardless either way will work equally well with Lowrance 2D or flashers.