The vapours from concentrated H2SO4 will chemically damage certain materials placed nearby -- I'm pretty sure of that.

The main danger with H2SO4, besides the burns, is its highly exothermic dissolution in water (which is why we add it to water -- which absorbs the heat and prevents spattering -- and not vice-versa). Your mixing container could become literally too hot to hold. Same goes for when you clean out your measuring containers.

For my B&W reversal needs I've been using a bleach composed of 65 g/L sodium bisulfate (pH Minus swimming-pool additive) and 10 g/L potassium dichromate. This is an efficient, stable bleach that (when fresh) does its work in well under two minutes.

I am a practicing chemist and wouldn't want to handle concentrated sulfuric acid outside of a fume hood (i.e. at home). Dichromates are nasty too, but since they are crystalline, inhalation/ingestion is not much of a risk (when they are handled carefully).

Your clearing bath should be composed of sodium sulfite (I use a 5% aqueous sodium sulfite solution). Metabisulfite clearing baths are used after permanganate bleaches and are not recommended for use after dichromate bleaches (I'm not 100% sure why, I have to review the chemistry of them.) After it's been used once, I find that the metabisulfite clearing baths develop a rather nasty sharp SO2 odour -- another reason to avoid them.

Any small spills of dichromate bleach can be neutralized before clean-up by treating them with a little bit of your clearing bath, which will reduce the Cr(VI) to the much less toxic Cr(III) and Cr(II).