Sorry old chap – these are in general not possible.
There is a limit to the size of algorithms that you can fit in a given FX. Any dual effects will probably exceed this unless they are pretty trivial.
Similarly, you can't have all programs xfadeable – they can only be so if they can fit in a single engine, as they both have to be present during the fade, which requires both engines to be active.
Many of these algorithms are large and complex – this is why they sound good. As a result, they take time to switch. Sorry.
