I actually did a lot of research before I bought...checking on various cycle forums, reviews, etc...the 550 is a nice blend of everything you need, plus, customer support is far superior to any other brand...I have a magellan for my car when I travel and the help is not very good...with garmin, you get a person, and that person knows what they're doing. The reason the zumo 550 isn't dropping in price so much is because it's such a good product...others drop quickly in price...I wouldn't trade my zumo in for anything...except, maybe another zumo!
The zumo was the clear winner. Read the reviews from motorcycle forums...there are plenty out there...