MildSeven- I agree with Luster and HellrotCi, you CAN'T beat the Griot's Boar's Hair Wheel Brush for gentle cleaning.
As I've said in other posts, even when the synthetic bristles are flagged, and thus VERY soft, the flagging will eventually wear down and then the brush can scratch. This just isn't a problem with the boar's hair. I used to use the synthetic brushes (including those from TOL) and they would EVENTUALLY scratch when a bristle lost its flagging and I didn't notice it in time. I've NEVER had this problem with the Griot's bushes.
I really like Irene at TOL and I patronize and plug her business whenever I can, but I don't trust ANY seller to tell me what's the safest/softest/best product. With regard to TOL's brushes, synthetic or otherwise, I've only had good luck with the small (toothbrush style) detail brushes no longer in production. And even with those you had to toss them before the bristles wore down.