To me, I don't find that there is any 'argument' either way (pro or con) regarding upgrading PROVIDED that said upgrade provides at least 1 of 3 tangible benefits:
1) An audibly noticeable improvement in sound performance;
2) A visually noticeable improvement in terms of owner aesthetics;
3) Replacement of a failed component with something touted as 'better'.
I do not agree with the idea of upgrading from item A to item B simply because item B has better specs. I need to either hear or see an 'improvement' - not convince myself I can hear (or see) an improvement because online strangers told me there is one...
That cynicism notwithstanding, IF I genuinely hear an improvement (or am more pleased with the aesthetics) I have no problem with the concept of 'upgrading' under those circumstances. But the idea of chasing numbers / specifications that do not provide me with some tangible real-world benefit does not appeal to me... and that distinction is anathema to standard 'audiophile' behavior to many.

