I'm also having very unreliable results with curve float.
1. It always animates my float in a very linear way, ignoring my curve entirely (even a simple ease in east out with only 2 keys, start and end).
2. It never ends on the value I specify in my 'To' field. Each time it runs my float ends on a different value. I'm not using any variables- I'm directly specifying the start and To values just to keep it simple. This happens no matter the 'Calculation' Method I use, 'none' or 'add to value'.
Not sure if there are some bugs with it, or if I'm just misunderstanding how to use it.