I'm in the process of upgrading electronics my 25' Parker SC...and looking to add a radar and chart plotter. Due to limited space, I am taking a close look at the radar/chartplotter combo units from Raymarine (R70RC), Furuno (NavNet 1722), and JRC (1800). Raymarine's unit is far more expensive than the other two (is it worth it??) Any feedback on any of these units or overall experience with these mfg. would be EXTREMELY helpful in making my decision.