Thanks for the great replies everyone.
The thing is i may not actually prefer the more 'natural' sound. I agree with the consensus that hifi can be subjective. I listened to the legendary quad electrostatic loudspeakers, and i was totally underwhelmed by what i heard. I was expecting to be blown away and instead i heard what to my ears sounded like a bland and lifeless sound coming out of two gigantic hunks of metal lol. Suffice it to say that for me personally, i much prefer the sonic character of conventional loudspeakers.
To get back to the amp issue, i like a sound that is not laid back (i almost like a birght sound such as my Cyrus amp). If the 909 sounds natural, i may actually prefer the mono amps. I guess iggs is right in that i should probably insist on playing louder in the shop so i can better compare the two different amps, or alternatively arrange for a home demo if possible.