Full support to @Zeb’s comment above.  200Mb for graphic intensive boards is nothing - and for any full user experience this is essential.

USE CASE:

We create Boards in our Global team and distribute it to our Country Partners to use. Its way too labour intensive to copy sections of a board (and blindly aim to get below 200Mb) or to copy and paste between accounts. This is senseless.  Also, we can host the board in our paid account, but if you are not the board owner, you do not have access to features such as “hide frame” (also a very silly restriction!).  In order for us to work effectively, a board can be created, exported and imported into a new (paid) account, irrespective of the size of the board.

Is there any workaround for this in the meantime? I have a board I need to load that is 243mb.

Miro support can restore them for you. Note: You will likely need to include a link to the backup on a service like Google Drive as the support form will likely not allow for attaching files that large.

You can open a support ticket by following theses instructions: 

https://help.miro.com/hc/en-us/articles/360020185799-How-to-contact-Miro-Support#h_01F010RXA0E1S9C0WFQYX75R6C

I think this could create some NDA issues, non?

If there is very hard technical problems uploading larger files, can we perhaps have some information displayed that would help us break down boards into pieces? e.g. when you make a selection for backup download it does a quick estimate on file size? 

I wasted hours trying to make this work that could have been avoided if the error messaging was worded more clearly: “Backups larger than 200MB cannot be uploaded. Please contact support for assistance.”

The error message for image uploads will tell you that your images have to be smaller than (something like) 8000x4096px, which is actionable. I immediately was able to resize my images and make them work on my boards. 

However, when I tried to upload my backed up files, it just told me the file was too large. No indication of any action I could take. So I started trying to manually copy/paste from the old board to a new board (which didn’t work because the images wouldn’t paste in despite me changing all the settings to allow it). Finally I started searching for help on how to upload large backups and after digging I found I could contact Support to do it for me. I would say I wasted maybe 3-4 hours trying to get multiple backups to work and trying alternate methods to back up and move Miro board content from one account to another. 

I understand that it might be a huge undertaking to make it possible to upload larger backups, but you changing text strings hopefully would be a good interim fix.