Access a supertype's delegated subtype

[Mike Pokraka]

Hi all,

R/3 4.6c. I have a SAP standard object with many subtypes and want to add
components that are common to all subtypes. So, extending the supertype
would be the cleanest option, but delegation does not get inherited.

In pictures:
SUPERTYPE --> Delegated --> ZSUPER
  |
SUBTYPE

So within SUBTYPE I can use SUPERTYPE.ATTRIB, but not the delagated
SUPERTYPE.ZATTR which I've defined in ZSUPER.

A way around this is to create an attribute (SUPER) of SUBTYPE and then
refer to SUBTYPE.SUPER.ZATTR. Bit of a long way around, but it works.
However I'm now in a setup where this will be high-volume and performance
could be critical. Perfect scenario for ABAP classes, but this is a 4.6c
system.

I don't know enough about the internals to know whether it's intelligent
enough to not re-instantiate the supertype (I suspect not), or indeed what
impact this would have if it does. Unfortunately I don't have the facility
to stress test - that's what go-live is for :-)
So, I wondered if anyone has any experiences in this or has any other
performance-friendly workarounds to suggest?

Any feedback appreciated.
Cheers,
Mike