Existing stand-alone forum db to wpForo

I have a - at times - high-traffic forum established in 2002.  Software (now somewhat obscure) is no longer being supported (for a few years now) and I want to move to the WP platform, not another stand-alone forum.  Have taken my time to evaluate options other than bbpress - as I'm concerned about handling higher-traffic.  I've run it as a single site on dedicated servers since 2006.  Going to move it to a WP-optimized cloud hosted solution going forward.  Current stats on the site:

76k+ topics
1.03M+ posts
10k+ members
1.4GB database

Earlier versions of the software added attached images into a table in the db... which takes up a large portion of that db size.  The latest version puts images in specified directories.

While I've moved the site from server to server over time, I've never attempted migrating the db to another platform.  Looking for any input on best practices in taking this on myself, and with tech help in-house.  What do I need to be on the lookout, or watching out for?  I already got the drift on passwords will need to be reset.  No biggie.  What else?  I'm not in a rush, but do want to start taking next steps sometime in the not too distant future.

Thank you. 

btw... one of the biggest "oh no's" with wpForo is there is no "ignore user" feature.  I read how it creates too much overhead, but I truly hope there will be another attempt to evaluate a solution.  Happy communities are easier to build when certain other community members can be ignored.  Even Twitter provides a great ignore user feature, let alone FB, etc.  It's now becoming an expected feature in communities.  It's a concern.  Thank you for your kind consideration.

🙂