Before I purchased the board you told me it would work with 3 thermocouples in this thread:
The discovery of that problem is very recent, the first person to try it was in september I think ( it could have been a bit before but I was away end of august/beginning of september ).
Jim Morris has said he would fix the bug, but is waiting on receiving his thermocouple boards to be able to test/fix it.
When you market the fact that your board supports up to 4 hotends, why is it so unusual to have two thermocouples? Do people really run one hot end on a thermocouple and the others on thermistors? That seems quite odd to me.
You are the second person I know planning a multi-thermocouple setup, the other one was very recent and discovered the multi-thermocouple problem.
Smoothieboard has 4 thermistor inputs, so you can run up to 4 hotends ( or 3 hotends and a bed ) on thermistors. You can also run 4 hotends and one SPI thermocouple bed ( I know of several setups like this, it sounds like the simplest way to a 4 hotend setup ).
Additionally, there is an extra ADC, and with a resistor and capacitor, you can turn it into an extra thermistor input, I *think* somebody is using this to run 4 hotends + 1 bed all on thermistors. If you have 4 hotends and a bed, you could theoretically do this.
Also - why on earth didn't you mention this in my other thread "Settings for 3 thermocouples". You could have saved me a lot of time by saying its probably not going to work, or you don't know that it works - or something!
At that moment I was aware of the multi-thermocouple bug, but it was very recent, and I missed the connection. Sorry about that.
This bug occurred because that functionality had never been tested. It will get fixed.