There's not a specific limit to DXL export or import sizes...

HCL Notes/Domino 8.5 Forum (includes Notes Traveler)

Subject:

but there are memory limits imposed by OS and system. I've been working on this code and reducing the amount of memory required especially for file attachments and other base64-encoded stuff. I haven't had a chance to do much with other types of large data, e.g. lots of rich text. There's also a crash we were getting with large attachments, more or less randomly, which has been fixed in 8.5.3. So you'll be able to handle larger attachments and handle them faster and more reliably in 8.5.3, but I don't have specific figures.

Disclaimer: As usual, nothing should be considered final until the product is released.

We do use file-based stream objects for attachments, so I don't know of any reason for particular attachment limits. Rich text has to all be held in memory at once so it may be more problematic.

Feedback response number AGUD8F3TFP created by ~Julia Prefootherlen on 03/18/2011