A general note on posting pictures on websites:

There are at least two different kinds of web places where you can put photos.

a. An "archive" site where you can place your picture, and can later retrieve the same image file. These are a lot rarer than most people assume.

b. A "sharing" site where you can post your pictures so that others can see them. In most cases, on sites of this kind, the image you send is shrunk, compressed, sometimes changed to another format, and otherwise mangled so that while it looks okay in a browser what you can retrieve is not the same image you sent for posting.

We posted festival pictures on Smugmug (mentioned above) for several years, and when we decided to drop the subscription I tried retrieving some of the images. They were all "standardized for the site" to the extent that I considered them "unusable" and gave up retrieving more than enough to show that they weren't even close to what we sent to be posted.

We had saved our original images, and the edited images we sent for posting, so there was no loss of images; but we didn't bother trying to retrieve all the clever annotations Lin had added on the site. (Some of her best creative hallucinations?)

A "migration" from one web site to another may or may not just copy the files on the original site to identical files on the new one, but since the two sites may have different ideas about file sizes, resolutions, compression, and the like you probably shouldn't just assume that they'll stay the same, or that they can be "retieved" from either site.

Just as there are well known rules for "safe sex" (often ignored) there are rules for "safe imaging" (even more often ignored). Even if you choose to take risks, it's better to know at least some of the rules. And if you plan on migrating, it would be a good thing to get it done while there's still time to figure out what to do about anything that doesn't work as expected.

John