texasbrit,
does it follow that we can make a rule of thumb from here on out that there will be NO diplexing of OTA at all, even between the 6x8 multiswitch and the satellite receivers? It sounds like it, but who knows -- if the satellite tells the multiswitch to send those other signals to it, the multiswitch might even convert frequencies, too, leaving UHF available on the multiswitch to TV line for OTA signals.

Just want to know what the limitations really are.

No diplexing of OTA is possible. The multiswitch does not modify the frequency, the signal comes from the dish all the way to the receiver without modification.

What kind of inputs would those be, are these "locals/internationals" some DirecTV service, how would we know we can ignore them, and doesn't that mean that six cables need to come down from the dish?

If your locals are on the 72.5 satellite or you are getting ethnic/international channels from the 95 satellite you need separate dishes for each of these and they connect into the two additional ports on the 6x8 multiswitch.
There is also some speculation that the "old" 4x8 (but not the 5x8) multiswitches will work for the new satellite since they pass the correct frequency band, but I haven't seen results yet from any experiments. There is also speculation that you can stack a new multiswitch above an "old" one - filter out the new sat signals on four outputs from the new switch and drive an "old" multiswitch (including OTA diplexing) for receivers not needing MPEG-4. We shall see...

I just recieved my new 5-LNB dish, I asked this question before ordering the dish from Direct-TV but I believe they gave me the answer I wanted to hear. I have the multi-switch that came with the dish, Zinwell, 6X8. The question I asked direct tv was can I still split out Anntenna/Cable signal from the Satillite signal in my coax lines. The answer was yes. Now that I have installed the dish, the answer is "no" this does not seem to work because HD channels are coming into the dish that are on the same frequency as OTA/cable.
Does anyone know if there is a way to split OTA/cable out of your lines with this new multi-switch? (Short of running seperate coax for OTA/Cable) I have cable running through my coax lines as well and would like to split it out so when the whether is bad I still have another source of signal. Thank in advance for any help. DJH