I haven't used them for coaching if that's what you're asking. But I have had lactate testing done many times using their methodology. I think it's a pretty good method for establishing your lactate threshold wattage or heartrate. I've had good results setting my zones using that method. FaCT Canada also used to sell powertaps - it's where I bought my first one - but they don't anymore.
Their lactate testing methodology is known as 'lactate balance point' testing. It tries to assess the effort level (watts and HR) where lactate is being introduced to the bloodstream (Rate of Appearance - Ra) as fast as it's being cleared (Rate of Clearance - Rc). This balance point is assumed to be your threshold. Above this balance point you're introducing lactate faster than you can clear it and essentially you're a ticking time bomb.
The methodolgy involves loading up the bloodstream with lactate using a step test - warm up, then step up 20 or 30 watts every 3 minutes until you're pretty sure you couldn't complete the next 3 minute segment. Then you immediately start a second step test below what your threshold would be. That way, you're working at a level where the lactate will be clearing (Rc) faster than it's appearing (Ra). At each step up in this second step test you have blood lactate measured. Even though you're stepping up the effort level, your blood lactate will continue to drop as long as Rc exceeds Ra. As soon as the blood lactate levels turn around and start going up again, you've passed that balance point.
Hope that helps.
Pad