I sat down and did some testing on the new BB Bastard .28g silica rounds that Jay was kind enough to give me a bag of. Two tests, with more to come once I can hit up the LZ;
Ballistic Eyewear test;
BA rifle @440fps from 10 feet. ESS NVG Profile smoke lense.
The silica rounds did not break, and did not deform leaving a small crater in the surface of the lense. The regular rounds did break against the lense, leaving an oily residue. You can really see just how much the stock bb deformed, the oily residue it left behind shows that a much larger area made surface contact than the silica round.
Someone had to do it, for science! So ow.... GBB Pistol @ 330 fps from 5 feet. The regular bb left a mark, no broken skin. The silica round left quite a mark and developed into a blood blister, did not break skin.
So far based off these two tests, the concerns over the silica rounds not deforming and henceforth transferring more energy to whatever they hit seems to be quite valid. There is enough of a difference between the two types of rounds that I would not ever use the silica rounds for a person-on-person game, only a CAPS session or target shooting.