I agree with bub4e, screwing into endgrain (screwing parallel to the grain) is never a good idea. Very low holding power and more prone to pull out. A shoulder is a good idea. By free tenon, I'm assuming he means a 1.5 inch long tenon on each end with no peg. This will key the beam into the posts and prevent horizontal movement perpendicular to the bent. A free tenon would be better than no tenon. Another option instead of toe screwing and free tenon is to use a spline.

In your case, you'd peg the spline in the post and beam. Use something strong and stable for the spline, Walnut, white oak etc. This would be a more elegant solution, and would avoid the use of metal hardware. Steel and wood don't really mix over the long term, in oak especially. The acidity will corrode the metal hardware and rot the wood surrounding the screw over the long term. Timberloks, which you may be thinking of using, are better in that they are epoxy powder coated, which would be longer lived than exposed metal or zinc plated.