Sure.. The google webmaster tools is very helpful if you decide to simply create a script to import you mappings into the Ceon tables.. The point is there are some fairly painless ways to accomplish this on a ONE TIME basis.. You won't regret the conversion to Ceon URI Mapping.. This IMHO is one of the BEST of breed for this class of apps for Zen Cart..
(BTW, are any of the "others" v1.5 ready??? Hmmmmmmmmm.. Haven't checked in on any of them in a while, but my guess would be NO..)
Another (kinda related) example on how the Google webmaster tools will help, I recently had a site which as converting from Joomla to WordPress.. I had to re-direct all those old Joomla URLs to the new WordPress equivalents.. I got the full list of links from the Google webmasters tools and created a spreadsheet that I imported to create the old to new mappings (there is a nice redirect plugin for WP that stores the redirect mappings in a table)..
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