The load-balancer-sku property can only be used when your cluster is created. You cannot change the load balancer SKU after an AKS cluster has been created. Also, you can only use one type of load balancer SKU in a single cluster.
If you want to use your own public IPs, use the load-balancer-outbound-ips, or load-balancer-outbound-ip-prefixes parameters. Both of these parameters can also be used when updating the cluster.
VNET Peering is now possible with SLB, it was not with Basic Load Balancer
Some gotchas: