WSIF overhead when calling plain java?

I'm considering using WSIF as a generic service invocation framework for a 
project I'm working on, specificially since it will allow us to initially 
implement "services" using simple java objects, but down the road to replace 
certain functions, like an initial hardcoded process with a more 
robust/flexible BPEL implementation.

This also leads me to think that we could use WSIF as a decoupling mechanism 
between most major components in the system, since doing so would give us 
massive deployment flexibility down the road, and system reconfiguration 
without requiring any code recompiles (ie. just change the WSDL).  Sort of a 
"poor man's" JBI.

So I'm curious how large the invocation overhead is when using WSIF to call 
plain Java class methods?

Is it big enough to be a concern, or is it small enough that I can ignore it 
safely?  I'll probably turn on service caching, to avoid the WSDL processing 
for each call, which should eliminate a lot of overhead after the first call.

Any/all insights into this would be very much appreciated.

Thanks!

Andrzej Jan Taramina
Chaeron Corporation: Enterprise System Solutions
http://www.chaeron.com