Good question. On the whopping two knives that I made I've left them pretty thin at the edge. The knife I posted was ht'd twice. The first time the ricasso didn't harden like I wanted (I was foolishly going for a hamon... too many things at once), and also, the very thin tip warped a little. If you decide to make a 2 brick forge I highly suggest a muffle. I'll post pics of my set-up if, later down the road, you decide to make one.
I wonder if the teeth on a file knife are stress risers? Anyone? On the files that I made klo's with I ground off all the teeth. didn't matter because they never got a proper ht anyway.
I like the rounding you've done. I'd have rounded the spine instead of the tang, but that's just preference. I don't much care for wrapped tangs and the rounding will make it more difficult to fit scales. On your next knife, should you decide to go with scales, attach the scales first then shape the handle to include rounding of the tang. Don't overheat epoxy though. Are you intending to keep the teeth on the spine? It looks a little weird having the spine above the plane of the tang, but a wrap should fix that. The belly of the tang looks abrupt at the guard and butt. I'm pretty picky about handle & scale shapes, but again, just preference.