Hi,
Site does look interesting, but i took a look at one of their articles: "Build a high efficiency inverter" and i see they are using bipolar transistors. Maybe they are using the older definition of "high efficiency" which was maybe 75 to 80 percent (back in the 80's before MOSFETs became so popular) but today high efficiency means 85 to 90 percent i think and will have to use MOSFETs. There are some really good bipolars out there but they dont seem to say what part number the driver transistor should be, unless i missed it.
Still an interesting site though.