I picked "other" since I figured a 600-3 would be sufficiently less expensive to produce than a 600-4 that I could live without the extra channel.

I tweaked the pricing model a bit to justify my choice :

$1 per watt
$300 per channel
$200 fixed cost (1400x1 + 8x300 + 200 = 4000)

That puts the 600-3 around $1700, vs. $2000 for a 600-4. I figure 99% of us would only use three channels.

FWIW, this model prices the three amps in the poll at :

1000-5 2700
600-4 2000
400-2 1200


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8