The filter caps in your power amps are much more vulnerable to breakdown since they are handling high ripple from the rectifiers (which is why they are also referred to as smoothing caps) in a warm to hot environment-and it is ripple and heat that are the two main causes of accelerated cap degeneration. I think you should be good for at least another 5 years on the Snaxo before considering any service. I'm not sure if routine service includes the Cermet trim pot replacements, as they are likely to get sticky over time. For the price commanded for a service, the money could almost certainly be used better elsewhere-or simply kept.
It may be that the like-for like replacement done during service replaces components with similar but higher spec ones....it has been a long standing discussion of which bead tantalum caps are the best...and certainly the latest yellow ones made by AVX are a modest improvement over the previous blue colored ones...which were maybe a tad better than the mustard color ones etc. If you are in the US, do check with AV Options about having the Snaxo serviced...they usually have a few 'extra options' that can boost performance above a standard part swap service that seem to not incur the incisive sword of the moderators.
