cookie format incompatible WP 2.0x and 2.3.x

It would appear that the dbx-pagemeta and dbx-postmeta cookie format differs enough between a WP site in the 2.0 tree and the 2.3.x such that anyone having to administer multiple WP sites of differing versions in the same domain will end up with “corrupt” cookies and an inability to re-order the password, template, timestamp, etc. Widgets on page and post edit pages.

In WP 2.0.x, the cookie format is comma delimited, and in 2.3.x it is ‘bar’ delimited. Aside from the obvious question as to why, when the content of the cookies is otherwise identical, my question is two-fold:

– where would I modify the source to standardize the delimiter character?
– are there any potential “gotchas” in doing so?