Raymarine A50D vs Garmin GPSMAP 526S

[waterant]

Hi guys,

I'm looking for a Chartplotter/Fishfinder for Great Lakes and maybe future coastal navigation and considering the units below:

Raymarine A50D
Raymarine A50D at Rogue Wave Marine

Garmin GPSMAP 526S
Garmin GPSMAP 526S at Rogue Wave Marine

Main features I'm looking for is at least 5" hi-res display and ability to add options later. Garmin seems to have better power output and dual frequency transducer. Not sure how important that is and if it worth extra $130.

Any feedback? Would you suggest another brand?
Your comments are always appreciated.

Thank you,

Ant