Curious if it's possible to truly utilize a second onboard effect (even if at the expense of a layer) ?
In other words, I know I can take layer A, copy to B and put a chorus on layer A and delay on layer B and adjust Program Volume of each layer, but the delay will be repeating the sound without the chorus. Great sounds can still be made this way, just wondering if it's doable. I realize I'm probably asking what may be a signal path question.
Unfortunately, there's no way to get true "Serial Routing" of the two effects engines, but you can use the method you are referring to, and apply two effects in parallel fashion. I you want, you can have one (or both) of the layer effects mixed fully wet too, so you don't get a doubled dry track. I've found this can get good results with using Layer B just for fully wet reverb.
Also, on a somewhat related note, you can create a performance modulation (mod wheel, exp pedal, velocity or other) that progressively mixes in a second layer. If you turn the VCA env all the way down on Layer B, and then target that destination from your mod source, it gives you a good way to dynamically mix the two layers together / or cross mix between them. Also, you can do some cool things like map note number in opposite directions to both layers so that as you progress up the keyboard it cross-fades between Layer A and Layer B.