I went Big Tumble at first, based on some YouTube videos.
I have a small, one-bag Harbor Freight cement mixer for, amazingly, mixing concrete. (It's great for that, by the way. Mixing even one 80-lb bag of concrete with a hoe is not fun at all, and I've used it for a surprising number of small concrete projects like mailbox and fence posts, and small slabs. But I digress.)
I bought the SS pins, added the Dawn and Lemi Shine, and then made a big mistake: based on a YouTube suggestion, I added some Nu Finish car polish, and probably added too much.
The entire batch of brass and the interior of the cement mixer turned into a horrible, sticky mess. So much for industrial-level brass tumbling. And it was noisy! Hundreds of cases banging around in a cement mixer is not pleasant. I even coated the interior with that spray-on bedlining plastic because the brass was being beat up. Another mistake. What goes on can come off. Now I had a sticky black mess. Rest assured, the cement mixer is exclusively for concrete now.
So I went small with the HF tumbler. Not liking the little rubber drums and their lids, I built the larger PVC drum. I even built a second, "backup" PVC drum, but have never used it. The one drum meets all my needs and I have never had any grimy, gooey results again. Just gray, dirty water flows out, leaving the brass clean.
As I have never had a bad result with the PVC drum, I highly suspect the rubber drums themselves were breaking down and coating the brass. And don't get fancy by adding some magic polishing medium like Nu Finish.
For years I vibratory-tumbled in walnut and then corncob. But cleaning brass like that is like dry-cleaning your hair. Water with a bit of detergent and Lemi Shine simply works better, is less mess (the walnut and media corncob can get stuck in the primer pocket and tend to migrate onto the floor) and give great results, even without the stainless wonder-pins.
As for losing the ability to tumble different batches at the same time, I just build up enough brass of a given caliber to fill the larger drum. I'm not in that much of a rush. Four hours goes by pretty fast. I can set it at night, too, and it's done in the morning, ready for a different caliber. So far, everything from .32ACP to .45-70 has worked fine in the larger PVC drum.
You can purchase a 2-foot piece of 4" PVC for less than $10, the glue-in plug and the removable plug at either Lowes or Home Depot -- but I'm boycotting HD because they came out against gun rights.
https://www.lowes.com/pd/Charlotte-Pipe-4-in-x-2-ft-Sch-40-Cellcore-PVC-DWV-Pipe/3223375