Replacing Capacitors, I Don’t Wanna!

Is the amp beginning to hum, make any other noises, or otherwise sound like it is going bad?  Does your amp run hot all of the time?  If it is not acting up, and it is not an amp that subjects its internal parts to high heat levels, I would not worry that much about the state of the capacitors.  You could have someone just take a look under the cover for bulging/leaking caps, resistors that look a little burnt, etc.  If your tech looking under the hood can do in-circuit tests of capacitors (equivalent series resistance (ESR)), he might be able to spot one going bad without big hassles and high labor cost. 

A preventative replacement of all caps seems extreme to me.

The problem with replacing parts with “better” parts is determining what IS a better part.  It is not always the case that more expensive parts with a popular buzz is the right choice.  If a part change can change the sound it can do so for better or worse.  I’ve heard tube amps whose sound dramatically changed in bad ways by swapping capacitors, in one case, very expensive Blackgates for cheap caps, making the amp sound broken.