If you try (curated) EAP 6 standalone-ha.xml configuration on WildFly the server will fail to boot due to an EJB3 subsystem attribute.

Server boot console log:

mbp:migration-tests emmartins$ ./default-config-manual-copy/wildfly-10.0.0.CR3-SNAPSHOT/bin/standalone.sh -c standalone-ha.xml
=========================================================================

JBoss Bootstrap Environment

JBOSS_HOME: /Users/emmartins/wildfly/migration-tests/default-config-manual-copy/wildfly-10.0.0.CR3-SNAPSHOT

JAVA: /Library/Java/JavaVirtualMachines/jdk1.8.0_40.jdk/Contents/Home/bin/java

JAVA_OPTS: -server -Xms64m -Xmx512m -Djava.net.preferIPv4Stack=true -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true

=========================================================================

11:37:25,583 INFO [org.jboss.modules] (main) JBoss Modules version 1.4.4.Final
11:37:25,896 INFO [org.jboss.msc] (main) JBoss MSC version 1.2.6.Final
11:37:25,985 INFO [org.jboss.as] (MSC service thread 1-7) WFLYSRV0049: WildFly Full 10.0.0.CR3-SNAPSHOT (WildFly Core 2.0.0.CR6) starting
11:37:27,307 INFO [org.jboss.as.controller.management-deprecated] (ServerService Thread Pool – 7) WFLYCTL0028: Attribute 'default-stack' in the resource at address '/subsystem=jgroups' is deprecated, and may be removed in future version. See the attribute description in the output of the read-resource-description operation to learn more about the deprecation.
11:37:27,307 INFO [org.jboss.as.controller.management-deprecated] (ServerService Thread Pool – 15) WFLYCTL0028: Attribute 'default-clustered-sfsb-cache' in the resource at address '/subsystem=ejb3' is deprecated, and may be removed in future version. See the attribute description in the output of the read-resource-description operation to learn more about the deprecation.
11:37:27,385 ERROR [org.jboss.as.controller.management-operation] (ServerService Thread Pool – 15) WFLYCTL0013: Operation ("add") failed - address: ([("subsystem" => "ejb3")]) - failure description: "WFLYEJB0451: Attribute 'default-clustered-sfsb-cache' is not supported on current version servers; it is only allowed if its value matches 'default-sfsb-cache'"
11:37:27,586 ERROR [org.jboss.as.controller.management-operation] (Controller Boot Thread) "WFLYCTL0193: Failed executing subsystem ejb3 boot operations"
11:37:27,588 ERROR [org.jboss.as.controller.management-operation] (Controller Boot Thread) WFLYCTL0013: Operation ("parallel-subsystem-boot") failed - address: ([]) - failure description: "\"WFLYCTL0193: Failed executing subsystem ejb3 boot operations\""
11:37:27,591 FATAL [org.jboss.as.server] (Controller Boot Thread) WFLYSRV0056: Server boot has failed in an unrecoverable manner; exiting. See previous messages for details.
11:37:27,594 INFO [org.jboss.as.server] (Thread-2) WFLYSRV0220: Server shutdown has been requested.
11:37:27,603 INFO [org.jboss.as] (MSC service thread 1-7) WFLYSRV0050: WildFly Full 10.0.0.CR3-SNAPSHOT (WildFly Core 2.0.0.CR6) stopped in 6ms

Attached is the standalone-ha.xml config, with just threads subsystem removed, and web subsystem migrated to undertow, that should be able to boot the server.