You should. It’s an improvement.

Not that the standard Grendel isn’t great too, but the 6PPC was king for a long time for good reason, and the 6 ARC is just a variation of that with heavier bullets.
On brass - Lapua is good if you can find it, but be aware that it’ll bulge at lower pressure than Starline due to the shape of the web. Hornady is fine too, if it’s all from the same batch. If not you may need to sort it.
Also, there was a time when some of us resorted to forming Grendel brass from 7.62x39 (the original parent case for all these PPC and Grendel variants). It’s not economical if you can buy brass, but if you can’t, it’s still an option. I’ve formed a few hundred with Red Dot and cream of wheat and a wax plug, or cheap 100gr SP pulls from RMR. If you sort them and turn necks they can be reasonably consistent, although it’s a large primer case of course. Just another option.
My #1 preference is still Starline, but haven’t seen any in a year or more.