However, as noted, the VERY first principle of advertising is to NEVER alter one's logo, even if you can better it. The consequences can be grave, so why spend a huge sum to create a an unnecessary risk?
I disagree, as do HSBC, Pepsi, Coca Cola, Barclays Bank etc.
A total (thus rendering it unrecognisable) change is definitely a no-no but a general updating I would suggest is sometimes necessary.
Here is an analogy. I don't really like the GoMoG logo (to the left). My wife, once a commercial artist, has often told me it could be slicker. However, it was the club logo for 25 years. Two of my departed moggie buddies (sorely missed) designed and had it made together. After 15 years on the internet, it is instantly recognised by 10's of thousands.
Do you think I should change it?

Lorne
The irony here is no I don't think you should change it if it is recognisable but I definitely do think you should update it. I agree with your wife entirely.
And on another thought do you really think your departed friends would really have wanted you to be stuck in a time warp just for their sakes? I somehow doubt it.
Of course what I also believe very strongly is that it is entirely up to you whether you change it or not. Your shout and your perogative.

BtG