The Sedona is a nice bicycle and bet that it came with better wheels than anythng you'd find at x-mart which is a major component and affects price. That, and your Giant is worth upgrading as time goes by while many x-mart bikes are nearly disposable.

With that being said, the stock wheels, especially the rear, was not designed to handle a 365 pound rider and this should be the first upgrade you make and may be the only one you need to make for a while.