Thats about right. According to Quickload it is just about a 6gr difference (about 7-8% improvement, which is a little more than a 338RUM AI from my understanding) . Quickload estimates between 150 and 200fps difference with the 250gr and 300gr bullets for the same pressures in a 28" barrel. I did a quick search here and saw quoted 100+fps difference in a couple threads. If it's only 50-75fps then there is no explaining the number of people choosing it over the 338RUM and the number of barrel makers that have reamers and supply barrels in the 338-300chambering.
I don't have any direct experience with the Edge and was only going on the estimates from Quickload.
If some is good and more is better, then too much is just right.
My mind is a raging torrent, flooded with rivulets of thought, cascading into a waterfall of creative alternatives