Imagination is more important than knowledge.
I do not know what the functional and/or technical aspects of your JAX-WS web service involved.
But as an Imaginary consumer to your service, I have some questions out of curiosity:
1. Even if JAX-RPC client is testing as suggested and working perfectly as of today.
Would that means the JAX-RPC client and JAX-WS service have common supported Data type
regardless of the underlying XML ser/des (marshall/unmarshall) mechanism OR it works by chance and not by design.
Unless the JAX-WS web service is static for ever, some questions (or obvious) need to be answered because things change
with time:
2. Data type aspect:
What happen if there is a change: a new field/property/element in the request
Let's say a data type that JAX-WS supports and is not supported by JAX-RPC client, then what happen in this use case?
3. Binding type aspect:
What happen if there is a change: a new attachment in the request
Let's say JAX-WS support MTOM whereas JAX-RPC won't, would the JAX-WS has MTOM disabled for the sake of the JAX-RPC client?
4. Contract type aspect:
If the intention is to support JAX-RPC client at all cost for business reason, would that imply JAX-WS a dummy JAX-RPC?
i.e, a developer who is supposed to use JAX-WS now has to know and/learn JAX-RPC (hopefully not a lot)
to support the backward compatibility aspect.