Performance of the unit itself issues aside, you'll be fine with only two outputs. When I first made my WB setup, I only had it going to a gauge, not the LINK. It was a pain to tune since the ECU didn't see the WB info, but all it took was more time. Log, adjust, log, adjust, etc, instead of adjusting and logging live (and having the outputs on the same graph). That's how cars used to get tuned on a dyno before in-car WBs were cheap enough to purchase.
Reading the link you posted I get the impression that the gauge output is not considered an output. So you have the gauge, then the optional WB and NB outputs. So if that's how it actually is, that technically has 3 outputs.