Just a personal observation and not the gospel but,
If you have made Eco Kits and Presets that are important to you, I'm not sure that BFD3 will help in that area as I don't think those convert up to BFD3. At least I have not been able to. If I remember correctly the Eco samples used a lower bit depth and fewer velocity layers.
All of my BFD2 stuff converts, and I am able to use that stuff and bfd2 expansions in BFD3, although the new BFD3 stuff really sounds great.