[DropTop]

I've been told by the guys at west marine to avoid the hummingbird brand sounders because the transducers are essentially unique to the model display you have them attached to. If you decide to upgrade at a later date to something with a bigger or color screen or add a chartplotter etc or the unit fails and you need to replace it in a couple of years, you will have to remove the epoxy or whatever you use to secure the transducer to the hull so you can replace it with another model, or leave it there and install another transducer next to it.

Garmin and Raymarine (among others I'm sure) have standard connection transducers that will work with just about any model display you want.

Whatever you choose to do, make sure you are thinking ahead for future upgrades and changes (and possible equipment failures), not just what you need to do today.