My opinion, but the copper in liverock/silicone thing is WAY WAY blown out of proportion. Inverts and Corals are able to handle some amounts of copper, which specific level that is, depends on the individual specimen.
I've had a couple different Leander shrimps that I've taken up to Seachem's recommended dosage for Cupramine, and they lived in that for > 1 month, without reaction.
I also have 40lbs of LR that has been in a Cupramine. That LR is in my 65 Reef (LPS, SPS, Softies, Zoas, etc.) right now, with no ill effects..