Limited how? People keep throwing this kind of talk around with nothing to back it up

It's a simple MAF-based system of timing, boost, and fuel maps (main + supplemental). It can be configured any way the owner/tuner wishes in open-loop, including effectively disabling the Subaru Active Ignition Timing algorithms.

With all due respect, I believe some of you are under some false assumptions and haven't done your homework on the topic. The misinformation is really bothersome.

The absolute largest reason people have opted out of using only EcuTek reflashing for their EM is because it requires visiting an EcuTek-licensed shop for any alteration. This pushes almost everyone away except the guy who wants a simple, safe, conservative flash-and-forget map. It does not in anyway whatsoever prove a single thing about the OEM ECU's capabilities or lack thereof. Combine that with people wanting to be "cool" and say they have a UTEC or people who feel they must have launch control and flat-shifting features or an ECU output to control a solenoid or two, and almost everyone just dives into aftermarket EM. Again, it says absolutely nothing about the capabilities of the OEM ECU other than it doesn't have launch control, flat shifting features, or solenoid outputs.