Using EJB for Web Services

Just finished developing prototyping web services using a simple Java class exposed as a stateless rpc web service to connect to Oracle. The java class simply packs/unpacks data and a PL/SQL stored procedure is called to do most of the work. The databases acceses are mostly simple get and update functions. We chose PL/SQL because we think that it will be more performant than using only Java.
My question is: Would it useful to use stateless session EJBs for our Java layer? What are the pros/cons?
Another question: Should we scrap the PL/SQL and use Entity Beans instead?
We were using JDeveloper for our web services during the protoype and deploying to 9iAS. But the client requires that we use WebSphere so we're migrating to WSAD, but we're still using Oracle as our database. What are the implications of this?

I'm shooting from the hip here, but what the heck...

Sounds like your using POJO's (Plain Old Java Objects) for your prototype. No problem there. Now let think about EJB's. Stateless session beans are distributed and transactional but these container provided services are not free. There is a price to be paid in terms of overhead, so you need to figure out if you need really need them. How important is J2EE to you? I would guess that interoperability (read J2EE) is an important consideration since you are using WebSphere in conjunction with Oracle. Since you already have the PL/SQL written, I'm not sure you want entity beans. I still subscribe to the K.I.S.S. principle, if you know what I mean. HTH

Thanks for your reply Howard,
Would there be a good way to test whether it would be better for me to use Stateless Session Beans or POJOs? How could I make it easier for myself to make an informed decision?
Daniel.