Any amp might or might not float ones boat and to that I say use what works for you. 
To the power rating issue I say total bunk.
Lets take my Crest CA-9 and compare it to the QSC PLX 1804. The 1804 easily trumps the CA-9 in output power (measure it or listen) in stereo mode using one side into a 4 ohm load.
Now take that and compare one side of the 1804 with the Shuttle 9.0 with the gains matched. The output is the same. The 9.0 will push just as much power as the 1804's 900 watts into 4 ohms.
Now compare that to the MarkBass LMIII's output into either an 8 or 4 ohm load. The Shuttle 9.0 trumps in Spades. There is no disputing this, it's not even close. It's not like an opinion it's a fact.
As to some having a perceived loudness as compared to the MarkBass amps, the MB amps are louder out of the gate but push them and they run out of steam quickly, while the Shuttle 9.0 as the Tortuous just breezes right on by and keeps going.
As to Kens comments, he probably has a need for some more efficient cabs. That being said he has had a bone to pick with Genz Benz for some time now so I would take any comments directed at GB with a large chunk of salt.



Smoothly stated or not a V6 while having many attributes is not quite the same as a V12.
YMMV
To the power rating issue I say total bunk.
Lets take my Crest CA-9 and compare it to the QSC PLX 1804. The 1804 easily trumps the CA-9 in output power (measure it or listen) in stereo mode using one side into a 4 ohm load.
Now take that and compare one side of the 1804 with the Shuttle 9.0 with the gains matched. The output is the same. The 9.0 will push just as much power as the 1804's 900 watts into 4 ohms.
Now compare that to the MarkBass LMIII's output into either an 8 or 4 ohm load. The Shuttle 9.0 trumps in Spades. There is no disputing this, it's not even close. It's not like an opinion it's a fact.
As to some having a perceived loudness as compared to the MarkBass amps, the MB amps are louder out of the gate but push them and they run out of steam quickly, while the Shuttle 9.0 as the Tortuous just breezes right on by and keeps going.
As to Kens comments, he probably has a need for some more efficient cabs. That being said he has had a bone to pick with Genz Benz for some time now so I would take any comments directed at GB with a large chunk of salt.


Smoothly stated or not a V6 while having many attributes is not quite the same as a V12.
YMMV