I am having exactly the same problems. Can we have an update from some the Magento team on what work is going on to improve the import / export process because the current fuctionality is simply not upto the job.
I am really impressed by Magento and think it will be a great platform, but unless I can find a robust way of getting data in and out on a scheduled basis, or be assured that it is in the pipeline I will have to look elsewhere. By data I principally mean Products, Category Structure, Related Products etc - .
I have used Demandware and their XML ( Real XML!) structure for importing data was great - (albeit little over complicated) but gave total flexibility for the FAST importing and updating of ALL data. If anyone at Magento wants me to show you some sample XML import data I would be more than happy to share it.