I got all of it tested. Flex 6600, PG XL SO2R amp, TG XL SO2R tuner, 8x2 4o3a switch. All components communicate via Ethernet so no PTT cables. Switching works well with N1MM+. Filtered by two low power bandpass filters + 40m VA6AM filter.
Testing revealed that the filters work but other problems emerged: internal isolation between bands in Flex 6600 and retransmission. Take transmit on 40m and receive on 20m. First, there is a S9+ 1 KHz wide second harmonic on 20 due to internal leakage in Flex 6600. It is narrow enough not to bother. Second, there is a 40KHz wide raspy signal around the first one due to retransmission from electr(on)ics around the house. I have heard that the source of the retransmission may be impossible to find. I was lucky to find that the raspy signal disappeared when either the lights in one area are switched on, or when the fuse to those lights is switched off.
So the triplexer and the band pass filters are fine. The biggest problem may be to find source of retransmissions, and they may be different on different bands.
Ignacy, NO9E