The Plinius SA-102 is a fine amp (though with a class A topology it will run hot) as is the Bryston (almost all speakers like more power) and the other amps on your list. But we chose to be dealers for Edge for one reason above all: quality. When you buy an amp you pay for the maximum number of watts and you pay for the quality of each watt.
From this perspective the M8 is quite underpriced, as it has qualities similar to that of the Edge NL series amplifiers - which are unmatched in the solidstate amplifier arena. The Edge will not add brightness to your system while simulaneously adding resolution and agility. You may find that the M8 will be much more powerful than the other amps on your list and control your speaker with a tighter grip, but it will not sound as 'loud' because it will not sound as 'grainy'.
That said, these are all good amps and all are very well-built and will last until you... 'out grow' them...