Thanks for your post.
The float datatype does cause problems in Data Compare from time to time unfortunately. It can occur when the two db's return the data back with slightly different precisions.
You can try ticking the option to "force binary collation" as this will occasionally result in them being reported in a way that they match. Asides from that, the other option is to create a view in each DB that will cast/convert the floats down to a lesser number of decimal places, and then compare the views.
Unfortunately you often cannot then sync these back as we only sync views back to tables on a simple select as far as I know (i.e. not where you have any functions)
We have a couple of bugs logged in this area but as yet I don't know of a timescale to get them looked at.