Todd - I am a strong proponent of the 2 ohm deal, since Thiels drop near 2 ohms over broad frequency ranges. I make a big deal out of the requirement because many current sources exhibit considerable anomalies as they run out of oomph. That distress shows up in many sonic results. And those results are blamed on the speaker as sounding x, y, z.
Amp circuits are quite individual, so the 2 ohm double may not always apply. And, as you say, something as big as that Classé is not likely to run out of power in any normal situation. Other amps in the family produce 3x the 8 ohm rating into 2 ohms. That topology is both stable and plenty strong.
My intent has been to advise against amps that are not stable driving 2 ohms. For instance the PS Audio BHK-250 stereo amp is rated as "stable into 2 ohm load", but in fact can only drive that load for short durations. It is not suitable to drive your 3.7s and PS will tell you that if you ask the right questions. Which is my point. Get an amp that will drive a 2 ohm load continuously.