WebSphere 9 upgrade with RAD 8.5

Our developers currently use the IBM RAD 8.5 to develop web applications (No enterprise Java beans (No J2EE), use Spring framework). The server team is planning to upgrade WebSphere from version 8 to version 9. Last I checked in the servers tab, RAD 8.5 supports WAS version 8, 8.5, and 8.5 Liberty profile. See screenshot.

Is it possible to continue to develop in RAD 8.5, and deploy to WebSphere 9 in the server environment? What kind of snag would I expect to run into? e.g. Assemble the WAR file in RAD 8.5, and deploy the WAR file in WAS 9.

Would there be any problem I should anticipate in the deployment descriptor? e.g. files like web.xml and application.xml?

Moving forward, is it better to use other IDE to do software development if we are not planning to upgrade RAD 8.5 to a newer version? Would MyEclipse(variant of Eclipse with better server support) or Eclipse IDE for Java EE Developers (oxygen) suffice? Do I also need the liberty profile? https://developer.ibm.com/wasdev/downloads/liberty-profile-using-eclipse/

What kind of issues should I be expecting? Or continue using RAD 8.5 would be a better option?

Here are some of the stackoverflow links I had checked already. There are pretty high level.

what-are-the-differences-when-deploying-on-tomcat-vs-websphere

can-a-war-file-be-deployed-on-any-server

Thanks.

In my experience I could not use RAD 8.5 to control a v9 server. I could not use Java 8 in RAD 8.5. I would not expect RAD 8.5 to know about the newer versions of JPA, JAX-RS and other things in v9. You could continue to develop jee6 apps on a v8.5 server and then move them manually to a v9 server.

Liberty is worth a look but is not completely interchangeable. Liberty has features that traditional does not (MicroProfile) and lacks some older things that traditional has (JAX-RPC).

You might check out the WebSphere Developer Tools for Eclipse that have support for traditional v9. They're not as full featured as RAD but might be enough. More info is at https://www.ibm.com/support/knowledgecenter/en/was_beta/com.ibm.websphere.wdt.doc/topics/wdt_overview.htm