Just curious if D2:R closed beta progress permanent. I’m wanting to test a druid build that uses spirit of barbs, but probably won’t finish before live launches. I know it sounds insane, but I think I know how to make it work.
I’m specifically asking for non-Season Bnet progress (I’m assuming I would keep any SP characters).
Thats a good question. But i’d like to know more about your build idea. If it’s not top secret. 
It’s not secret. It just exploits the fact that different forms of thorns are stackable (at least according to the interwebs).
Basically if you use Bramble as your Armor rune word, you get a thorns aura. Then you could use Iron Maiden from Rift rune word for even more thorns.
Then you take hunger on a werebear or werewolf and basically eat stuff to stay alive while they die attacking you.
You also get extra damage from the rift rune word itself as it procs spells when casting. I was going to also do Fire paws + 20 points into fire elemental skills of fire damage when I needed it on a Phys/ice immune (as I intend to take the cold merc from A3).
Though you could make this build without taking spirit of barbs, it just won’t scale with + skills. Bramble also gives charges of that.
Beta progress historically is not kept between Beta versions and Live. I am not expecting any progress to be kept.
Further, while Blizz had the Closed Single Player Technical Alpha in Feb, there has been no mention of a Closed Beta yet. They have only talked about an Open Beta later in August.
I was beginning to think that you abandoned us for the D2R forum. 
I would be surprised if any testing progress is made permanent. Personally, that makes sense, because beta means testing and items and experience can be gained through exploits. Now if it was termed “early access” then I would expect things to be carried over.
No. Beta is not demo. There’s gonna be bugs and changes would need to be made when transitioning from beta to release.
WHAT’S NEXT?
This August, players will be able to experience these latest changes firsthand! For a limited time, the gates of Hell will reopen, allowing players who preordered Diablo II: Resurrected to step into Sanctuary in the early access beta. Soon after, all players (on PC, Xbox, and PlayStation) will also have the chance to confront the demons of the Burning Hells in the open beta.
No. everyone starts fresh in the final version.
“* Early access to the Diablo® II: Resurrected™ Open Beta will be available prior to the launch of Diablo® II: Resurrected™ to players who purchase before early access to the Open Beta ends. Actual platform availability and launch date(s) of the Beta subject to change.”
No mention of the CLOSED Beta.
In the past early access to the Open Beta has meant 2 days early.
Fundamentally, D2 original and D2:R are the exact same. Have you tried this build out on vanilla D2? Might be a good idea to just try it there first.