Migrating from RoboHelp (old version) to Zoho Desk Knowledge Base (Insights & Approaches)

Good Day, I have a client who is currently within an Old version of RH. I'm a big RH fan, however they don't have the skillset to maintain and update. They have begun the journey with Zoho Desk, thus they now how a Knowledge Base. 

My topmost requirements: 

a) How to export the data from RH and maintain the STRUCTURE (the TOC)

b) How to export and maintain the links (they have 3000 pages, all interwoven)

c) We are ok with dropping the images, as most are probably dated. Since we will review/update the pages/content, we'll grab new photos, so don't need to carry over the images into Zoho Desk

A few questions:

a) Has anyone made this migration, RH to Zoho Desk (or similar CRM), any insights? 

b) Has anyone made this migration and messed it up badly (smile!) or would like to share their top do's and don'ts. We are interested.

We are tinkering with the idea this week since we had the main RoboHelp folks all RESIGN - leave the project, so probably no better time to make the move to a more 'open' tool that resembles a wiki doc for ease and contribution from the staff. 

If you have migrated from Robo Help to another tool, what are your insights? I've gone from RH to MadCap Flare successfully.  Thank you for allowing me to ask and share!