Welcome aboard Casey!
No matter what brand of marine electronics you're currently running,
http://www.airmartechnology.com/ makes the best transducer available for it.
Their website is a treasure trove of knowledge regarding this vital piece to the fish-finding puzzle.
I'm running an Airmar 260 right now and it's an amazing unit but if I has to do it again, the beam width of that 270 would likely get the nod.
There's really no wrong answer here as both units will serve you well but if you're a downrigger angler and you like to see your weights on the screen then the 270 is the better choice for you.
Don't overlook the venerable P66 and there are several CHIRP transducers available as well if your unit supports this cutting edge technology