I don't think OER (or PfR) will split traffic from what it considers a single flow. At the most basic, OER manipulates routing table entries but it also supports PBR at a more advanced level. (At lease I think OER support PBR, if not, then it's PfR that does.) Unless you can get OER (or PfR?) to see different traffic flows, you may be unable to get it to load balance.