I"m exploring two options for console, one 12" Helix Mega or two 10" Helix units, one being mega. Do people prefer one 12" at console vs. 2@10"? I think it would be nice to run maps/2D on one unit and Mega Side imaging on the other. For the older 10" Gen1 unit, is one version prefered? For example if I went the 2@ 10" route, should I get a gps/sonar, DI/sonar, or si/sonar unit Gen1 unit to go along with the Mega unit?