The RCE yellows won't work with the stock struts, not sure on the blacks though.
You mentioned Koni struts on your MS3, which is also a good option with the RCE springs on the WRX ... So that is another way you could go. I personally just prefer a good strut/spring combo to coilovers ... Especially on a DD.
Just keep on researching and keep us posted ... Seeing a new member actually making informed choices (with quality parts) is a nice change around here lol.