Looked like a solid hit. If I was to buy, I'd get the 400 over the 350 Legend, then handload. I was around 3 hunters using the 350 Legend this Fall, not impressed.
I'll admit, one has to do correct shot placement, also researching the best bullets with either factory ammo or reloading.
The first experienced hunter shot a 300lb+ black bear at about 30-35 yards. The hit was fairly good, bear on the ground for a handful of seconds, maybe stunned. His buddy filmed the encounter, said his 350 Legend 'did great on deer'. We gave it some time, tracked until midnight as the sparse blood trail disappeared.
The 2nd shot a 10 pointer in IL, went about 40 yards. The shot wasn't perfect, but worked.
The last hunter, kinda new, had issues. The one buck I think he hit had zero blood, the deer was momentarily down. The distance was reasonable, almost like he stunned it with an antler hit. I suggested he take a close shot with an anterless to start. Yes, he had permits. He admitted he got nervous before the shot, so anything is possible.
I set up my 444 Marlin for IL deer hunting, ended up just using my most excellent Knight Elite M-L. I just took one coyote and an anterless.
For shot placement I prefer the aft edge of the foreleg, 1/3 up from the bottom. The deer may not be totally broadside, I'd prefer to angle forward. During field dressing the top 3rd of the heart was destroyed. Most often with a 'soft tissue' shot, one gets an exit. I was using a Barnes copper bullet with a good charge of B209 powder.