Recip tools are very useful for the right application. Notching aint one of them.
The fein (and bosch-alike) tool is fine, but won't be as quick as a skill/rip saw.
As said, skill saw, then chisel. To be honest most of the time, you only have to wedge the chisel in, wiggle it and the lump of wood cracks out whole. Then tidy it up with the chisel. Don't run them too deep (as I often did when I first started cutting them) and don't run them through the middle of a room (as a mate of mine did, which meant the whole floor bounced, and was basically knackered).
There are loads of set rules laid out in books. This amount of depth in this size joist and this far from the edge....blah...blah...blah.
Who gets a text book out to cut a notch!? Just use your common sense.