Yeah, but after you have updated paths/registry old client becomes unusable. And if your application is the only application that uses oracle client, why do you have to trash user workstation with old files that are not in use? :) Of course it all depends on attitude, but I fully agree that both approaches can be used in practice. It's like optimistic vs pessimistic locking :)
When we need to install new version, we move the software to a new folder on the file server. Then we run a logon script that just update the paths and registry and the user is working with a new client software. Just curious, why do you want to uninstall old client? Just leave it there.
-- Best regards, Edgar Chupit callto://edgar.chupit