I thought I would remind everyone about one other important limitation when doing these big imports. You can only delete a maximum of 500 contacts at once in gmail. So, if you've got 750 contacts, and they're all dorked up and you want to start over, you would think that you could just press the "Select All" button and then "Delete Selected Contacts", but G will complain. So you then have to go down the line, deselecting individual contacts one at a time until you get to where you have 500 contacts selected and then you can delete them. So, if you are doing a big import, I would HIGHLY suggest that you start small to make sure everything is working good. Try some of your trickier contacts--ones that have the most fields filled out--to make sure everything goes where it is supposed to. Once everything is hunky-dory, then upload the whole thing. Good luck!
(Originally discussed here http://rabroad.com/forums/6120-post16.html)
