A friend of mine got the 55 and I shortly after got the 45.. the color thing is not worth any extra cash IMO but to each his own. Don't remember if the protective soft case comes with the 55 or if you still have to buy that extra but they are nice. I don't have one yet.
Very quiet operation
Easy to use
NO Interferance Problems...
I also took the extra cable off.. my understanding is the only reason it is put on there is because there is a patent on the self leveling transducer like a vexilar. Not 100% sure on this.
MarCum doesn't use it but they have the arm thing.