I cannot find Remington but did find 50 new cases of Nosler locally.
Anyone have experience with both.? I suspect that once I select one brand I cannot switch back and forth for reloading.

If I were in your situation, I'd buy the Nosler & use it if you need brass. If RP does become available again you can use that too. Load data may or may not be interchangeable. Just keep records of what you do so there's no confusion in the future. It's all part of the fun.

I was lucky enough to score these 2 bags a few years ago. Though it might help if I ever decide to sell my 350 RM.

I've been using mainly Rem Brass for 40+ years with no issues. Never used Nosler. The only other brass I have used is brass formed formed from other magnum brass. I had no issues with those either, but brass is fairly easy to come by and I have not done that since right after I started shooting my first 350.

Once upon a time, Remington made Nosler brass. They just made it to higher standards than their own. Now most (but not all) Nosier brass is made by Norma.

Brass differences matters in reloading. Check the case volumes. The closer the better, bit if there's a significant difference, you will need to work up your loads with each.

Never used Nosier brass A S. I use the factory ammo that came with the gun and Hornady brass bought a while back. Be Well, Rustyzipper.

I did manage to pick up a bit of brass in the form of reloaded ammo and some 1X fired. All Remington. Right now the biggest issue is finding some Speer 180 grain flat points. My goal is to load for a hot 358 Win level. Gun is a Remington 660 and I expect recoil to be on the harsh side, even at this level.
Sadly, I am already eyeing a Remington 673 for the 22" barrel. I suspect that the 350 Rem will cause me to sell off my Ruger 338 Federal

Dingo,
You probably own HALF of all 350 Remington brass in Australia

This is turning into my quest.
I knew better than to buy the gun but it is so intriguing.
And the price was cheap.

Worst case... I will buy a form and trim die and scrounge sone 338 Win mag brass to form.

I did locate a gentleman that had just overy half a box of Speer 180 gr JFP to try against the Hornady 200 gr spire points I still have from a 358 Winchesyet

I have a box of Remington 200 grain factory and a box of 250 grain factory ammo, but I hate to shoot those as someonethat doesn't reload might need them.