[Dionyz]

To a certain degree you are all correct.

A lot will come down to the normal listening level in the home and the degree of clipping (inaccurate reproduction) you are willing to accept.

1 - I would be extremely unsatisfied with 84 sensitivity speaker output in my home theater. These just have no way of performing satisfactorily in my home theater, especially with a 100 w/ch receiver.

2 - The Klipsch RF-83s, despite their very high sensitivity, have impedance dips to around 3 ohms in certain frequencies. As I said these speakers love power. When watching movies with the Onkyo 905, I have the volume at around -3 to 0 dB. I do not turn it up more as I do not want any clipping during the peaks. And this is in a temporary location with no sound treatment. When I move my system into my HT with sound treatment, when it is finished, the Onkyo will not have sufficient power.

3 - Dynamic peaks are what drive the need for power, not average loudness. The 20 dB dynamic peak is an average. Certain sounds require well above this level, pushing 40 and up to 60 dB. If you don't care about clipping and the associated distortion and missing reproduction, then you may well be satisfied with low efficiency speakers with an average receiver.
However, if you care about faithful, undistorted sound reproduction - if you know what it sounds like with high quality and efficient speakers, then you want the most power you can afford. That is why even the RF-83 speakers NEED more than 140 watts/channel for pure and unclipped dynamic peak reproduction.

Bottom line is that it all depends on what your listening habits are, combined with your expectations.

YOU, not I, or anyone else should be the judge.
I only offer my OPINION and attempting to raise awareness.
I am definitely not telling what others should do.