I am running Angel Bob + Maraxis and am running into a startup failure:

'Error while running setup to entity prototype "thermal-accumulator" (heat-pipe): next_upgrade target (bob-heat-pipe-2) must have same fast_replaceable_group (heat-pipe != heat-accumulator)'

Maybe the thermal accumulator needs to set a different or even unset its upgrade target.

Uploaded a new version with the fast replace removed. Not sure if it is going to work, but you can give it a spin and see if it is resolved :)

Updated to 1.4.6 and the same startup failure appears. :(