Just installed Bitwig 1.0.5 64bit demo, added Spark 1.7.2 64bit and when I tried to load (button) a Project, BitwigPluginHost64.exe stopped working.
Clicked Bitwig's Reload plug-in (a nice novelty feature of sandboxed VSTs)
This time, I used the Library (mode) to load another project and it plays fine.
So, new DAW, there's some rough edges to fix between it and existing plug-ins.
I'm pretty sure Bitwig will get into Arturia's list of DAWs when beta-testing new versions of their instruments