To sorta answer your question (I have used SS media, but that wasn't your question
) I have worked in a shop where parts were tumbled to both remove burrs and for polishing (depending on media). For deburring, ceramic pieces of various shapes (cubes, pyramids, balls) are used, mostly wet. Also hard plastic pieces are used (I got some pyramids from HF, about 3/8' tall), and I've tried this one wet and dry. I have not used any glass beads for "tumbling" but did use some fine glass sand/beads for bead blasting parts.
When I first started "tumbling" I experimented with different media (dry). I used the normal stuff; crushed walnut shells (the dark coarse grind lizard litter works better than the "Desert Blend") and corn cob media. I also tried dried beans, beach sand (too heavy for a wobbler), rice, wood chips, BBs, small SS nuts/washers/screws (wet), sawdust, plain solution (water, soap, vinegar) w/no media, and prolly a couple more that I can't remember. Some work, some don't, and none stand out.
After a few years I settled on this
http://www.drillspot.com/products/499763/econoline_526020g-40_40_lbs_blast_media For some high gloss polishing I'll add some auto polish, and some deep cleaning I'll add some plastic pyramids.
Experiment. Try rice or whatever you think might work. Most will not harm your brass and you'll get different finishes from different media (hard ceramic and plastic will leave your brass an even dull, matt finish, walnut will leave your brass a semi-gloss, and most of the time you'll get high shine from corn com)...
But, FWIW; to me it's all academic. I reloaded for 12 years before I started tumbling my brass (rotary and wobbling). I merely wiped my cases with a solvent dampened rag as I inspected it before processing.
Nope I didn't ruin any dies, and
yep, I could spot any defects. Today I clean my brass in whatever is in my tumbler, and I only polish brass for my Garand and my 45 ACPs (that fling cases hither and yon), makes them easier to spot in the dirt, rocks, trash at my "range"...