People always ask how many channels can I record. If you ask, how many transponders can I record, that gets rid a lot of the misunderstanding, although there will need to have more details later.
Single tuner (not FBC) plus universal + Single signal supply = You can view/record one transponder. You will comfortably record/view 12 channels without a problem. Excluding encryption issues
Multiple tuner (not FBC) plus universal LNB + Single signal supply = You can view/record any one transponder + one more on same plain(quadrant). Universal LNB is locked into high/low, vertical/horizontal plain
Multiple tuner (not FBC) + multiple universal LNB = You can view/record any two transponders if you have two tuners. The LNB ports are independent are each will do what it needs.
As an example, if you have a single Terrestrial tuner. You are locked to one transponder/multiplex. You are not limited to one channel. You can record all the channels on that transponder/multiplex. For the UK, as an example, most people will be able to simultaneously watch/record BBC 1 HD, BBC2 HD, ITV 1 HD, Channel 4 HD,
FBC tuners do not need unicable and will work with universal LNBs. You wont get full benefit. I have got to 30 channels using a universal LNB.
An FBC tuner is 8 tuners. 2 have signal wires connection points , other 6 do not.
If you use a Unicable LNB/switch, you can record as many transponders as you have tuners configured. It is not 8 channels, it is 8 transponders
FBC Tuners + single universal LNB
You can record from any one transponder. The other 7 tuners will work in loop through mode. So you can record as any channels as are on all those transponders
FBC Tuners + twin universal LNB
You can record from any two transponders The other 6 tuners will work in loop through mode. So you can record as any channels as are on all those transponders