There are a few ins and outs to it. The ebrake is a pain to hook up, there is some uncertainty as to the setting on the proportioning valve, the holdback valve may present a minor problem, so in theory some issues about front rear bias.
Several people have done it with no major ill effect. If you do it put in SS lines at the same time, much easier then than later. A big advantage IMO is the ability to install SS lines and a bigger choice of grippier WRX pads all around, like Axxis Ultimate. So if you bother at all, go all the way.
Oh yeah, insurance can be an issue. If you have an accident, your insurance company can claim you were "tampering with your brakes", especially if brake failure (unlikely) is the cause. Best to get a licenced mechanic to do it anyhow.
Try searching this forum, keyword drum, any date, lots more info.