Anyone any experience / advice about retro fitting a Bafang mid-drove motor?

Building a new bike for my wife, so have a rigid inbred 29er that will likely be surplus to requirements. The ride into town requires a substantial climb in either direction so thinking the inbred could be repurposed into a utility bike which all members of the house can make use of.

I guess I want to know if the Bafang motors are any good (the climb up our track requires a lot of torque to get up!), how easy the ordering and install is, and most importantly will the batteries burn my house down when being charged

Can't speak for retrofitting a midmount but I have a wee Orbea Katu-E electric shopping bike with a bafang front hub motor. Have had it since about 2017 I think?

Never had an issue with batteries or charging it up. The control system was made by eBikeMotion, now Mahle.
It does occasionally turn itself off but it goes back on again!

Power-wise it's fine. You can tune it with an app and I have it on about 60% when it is on "full power" setting if that makes sense?