regarding the BRZ and other newer Suby motors, there is a workaround by using an emulator to trick the ECU, however, as far as I know there is only one source for them, out of Australia, and when I was first looking into them they were still pretty new. The idea of having your entire driveline reliant on a single part with a single supplier that is over 5000 mile away was just a bit too much for me.
Regarding the EJ25, we take a lot of extra steps to ensure they are as trouble free as possible. I don't advertise everything that we have done to a motor, but I'll say that we address head gaskets, heads, valves, oil pump, oil pan, pick up tube, baffles, and some others. The EJ25s have not been 100% without issue, but we've been able to resolve the things we've encountered over the years and to date have not had any head gasket issues.
As for Outfront, I've used a few of their motors in the past and I was very happy with them overall, however I wanted more usability and found that in the stock ECU, which led us to the packages we recommend now. In addition, there are some states that actually check the engine number, and a JDM motor has to be EPA certified and approved for use in the US. Fortunately for most Suby users, 90% of the states don't bother checking the engine number, and this is how so many get away with using them. Hell, my daughter may even have a JDM in her bugeye... ;-)