Tapping the magazine isn't necessary. HPA rigs are popular for steel plate shooting in Japan, as magazine changes aren't a requirement. They'll typically run their magazines at full capacity (31+1 rounds) and reload in between rounds.
As far as accuracy goes, HPA setups are the most consistent way to get gas pressure output. Japanese competitive shooting organizations have completely different outlooks on their sport than anywhere else in the world, and as such, I wouldn't consider such a setup in any other country.