We upgraded EBS 12.0.6 to 12.1.3 and Database 10.2.0.4 to 188.8.131.52 . As part of the upgrade we configured Internet faced Load balancing for 2 nodes and intranet faced Load balancing for 4 nodes , It has 2 shared appltop respectively. It’s possible to accomplish this type for upgrade through Maintenance wizard.
At this point Maintenance Wizard 2.19 does not include support for RAC or Shared Appl Top. I'm not sure that the load balancer's would have any effect on the Maintenance Wizard tool as you are working at the operating system level throughout the upgrade process.
We do anticipate releasing Maintenance Wizard with Shared Appl Top support in the near future.