merge waypoint data from separate devices

I'm reposting this since I still have to deal with this problem and find the previous replies incomplete.

I have two devices with different waypoint data. I would like to merge that data together.

I understand how to get the bcnav/data files off my device and have done so. However, That is only one step of the process of merging.

According to one reply, a merge can be done by exporting to GPX format and then, I presume, I can merge two text files together by hand. However another poster said GPX loses some BCN data, but didn't elaborate.

So, should I use GPX? If so, what data may be lost (maybe I don't care). And, are there any cautions of merging the two text files?

Another possibility, now that we (or at least us early adopters) have bcnavxe, I might be able to do the merge online. Anyone know of how that works?

Thanks.