Hoping we can get some educated comments from those who have extensive experience with both.
I've had great success with the 299 in the .30-06 (as well as in the .303 and 7.62x54R in its 314 and 316 variants), since I was guided to the bullet by a casting mentor.
I believe the 284 was originally conceived of as a Krag bullet, but its design does get away from the 299's bore rider nose design, and as such, I'm theorizing it may be a little stouter and have some edge if choosing to increase the velocity. I do know it has quite the following, but I have never dabbled.
Tell us your learned tales.