Silicon vs Herbies tube dampers on Cary 300B amp

I am looking for some feedbacks about these pretty cheap silicon dampers that you can get from Ebay or just here.

My amp is Cary CAD 300B SEI and I would like to try them on driver and input tubes, but the question is, is this going to improve the sound and in which way.

Also looking at Herbies, but the price differences are pretty huge, especially if you go for RX version.

Iam reading differ things about Herbies, where some very negative ones, but on the other side good about these cheap silicon's.

Of course, the best way to find out is just get them both and compare, but maybe someone already did this and thats why I am placing this thread.