It is really not that complicated, turn on 64 bit float engine, restart Cubase, load your project.
Look at the performance meter in Cubase and on your computers cpu usage.
Is there any difference? For me about the same, some projects have even better performance.
Are the data calculations done more precise YES
Can it possibly improve the sound quality, something subtle that I don’t hear (yet) YES
Why would I ever go back to using the 32bit float engine?
Just the potential of sound improvements without any cost, makes it worth flipping that switch IMHO