I'm about to purchase a 4pm,that comes with 2 x R334SB and not a bad deal price wise here in Aus..although I probally would prefer the R304SB with single antenae and use a 400mm ext aerial,but the shop doesn't stock those,,but has the R314SB,which I think is similar to the 304,and I think compatible with a 3pv,but not sure about the 4pm,as the 314 isn't listed on the compatibility chart,Ive always used a long antenae on my boats,without problems,,so not too sure about those twin antenae diversity setups,,opinions appreciated