My experience is as Marco describes. When you download your tree from ancestry, you do not lose the data regarding who originally submitted media. When you upload a new to from FTM to ancestry, you do lose that data.
However, if you download from ancestry you will end up with a database where all of the children in random order, instead of birth order, spouse order and preferred spouse will be randomized, you will lose all notes other than person notes, and any media categories you have created will be lost...
Basically, you have to decide which is the lessor of two evils. When I add media from other trees, I have gotten in the habit of appending the description to add "Originally submitted by user-name to name-of-tree on date-submitted." In the event I lose a sync and have to upload a new tree, at least that info will be preserved, even though it will no longer be hyper-linked to the original submitter. Unless my FTM file itself is corrupt and I have no choice, I will not download another tree from ancestry to FTM as cleaning up the database is simply too difficult...
I do think the developers need to find a way to address the issue regarding the lost "credit" for media from other trees as it is becoming a source of great frustration for people.
However, if you download from ancestry you will end up with a database where all of the children in random order, instead of birth order, spouse order and preferred spouse will be randomized, you will lose all notes other than person notes, and any media categories you have created will be lost...
Basically, you have to decide which is the lessor of two evils. When I add media from other trees, I have gotten in the habit of appending the description to add "Originally submitted by user-name to name-of-tree on date-submitted." In the event I lose a sync and have to upload a new tree, at least that info will be preserved, even though it will no longer be hyper-linked to the original submitter. Unless my FTM file itself is corrupt and I have no choice, I will not download another tree from ancestry to FTM as cleaning up the database is simply too difficult...
I do think the developers need to find a way to address the issue regarding the lost "credit" for media from other trees as it is becoming a source of great frustration for people.