you're fooling yourself if you think looks don't count. play a formal jazz gig where everyone's wearing tuxes and you wear a t-shirt and sandals. or play a rock gig where everyone wears t-shirts and sneakers and you wear a tux. or play with devo where everyone wears a yellow hazmat suit and you wear anything else but the yellow suit.
now use that logic with amps...show up to an allman bros gig with no amp, or show up to an ampless gig with an svt...see how quickly it takes for you to be shown the door.
looks count a great deal. those who don't believe looks count usually end up not getting many gigs.
also, regarding an earlier comment...maybe for you and mama dave the amp is just a monitor. well i tried that route the last couple weeks and it isn't working for me. i don't like the sound, so i'm going back to using a mic on my amp, which makes it way more than a stage monitor...it makes it the way i get my sound to the crowd. and any soundman who complains i'm too loud is incompetent. i am NEVER too loud
so as you can see, the actual answer is "
do what you think is best."