Contact list management woes

I've been managing an ever-growing list of contacts that I've collected over my time in the industry. As this list has been moved from device to device, from collaborative system to collaborative system, all sorts of problems have been introduced in the list.

What appear to be duplicate records each contain slightly different information.  How to separate today's fact from yesterday's history has become a problem.  Services, such as Plaxo claim to have a solution to that problem.  They periodically reach out to everyone on the list and ask for an update.  Since I never respond to such queries, I have trouble believing that approach would work consistently enough to make it worth subscribing to such a service. I'm sure that now I've mentioned it, I'm going to get quite a number of proponents of this type of service to reach out and educate me on their benefits.

As the contacts have moved from repository to repository, formats for telephone numbers, Email addresses and other such things have become jumbled.  Each system believes that its own format is the one that should be used.  When the contact information has been synchronized from smartphone to computer, other interesting changes have been made to the data as well.

The data has been moved into and out of Open-Xchange, Zimbra, Microsoft Exchange, and Google Mail. Each move has done weird, wild, strange and wonderful things to the data.

Some suppliers of smartphone software appear to feel that the notes field is theirs for use in any way they feel useful.  So, fingerprints from Palm, Apple, HTC, Microsoft and Google software can be seen scattered throughout the contact list.

I could manually go through and fix all of these problems, but the list now includes over two thousand entries and grows regularly. I don't want to invest that much time in fixing things when the list is usable now.

Is is just me or is contact information becoming increasingly difficult to manage?