Each EFIS product uses its own internal sensors for almost everything but magnetic heading. Each does require its own EDC-D10A remote compass though.
The one exception is that a single OAT can be connected to multiple EDC-D10As to provide OAT to both EFISes.
You can split the GPS serial output from the 430 to drive the HSI on both EFISes units, but note that if you want the HSI to be driven off of the radio side of things, or if you want to fly LPV WAAS approaches, you'll need our upcoming HS34 HSI expansion module.
