I'm not sure I can agree–seeing 'ſ', where I'd ordinarily expect to see 's', was briefly confusing at first, but I quickly derived from context what it must mean, and found my surmise confirmed in further perusal of older texts.
On the other hand–I'm not sure that someone, who has written an Emacs minor mode to perform automatic ſ-insertion where it is grammatical to do so, is necessarily best placed to speak to the general case here.
I don't think the parent poster was talking about being confused as to the meaning; rather, they're talking about the presence of these characters impeding fluent reading speed even after one knows what they are. Enough of these changes and you feel like you have dyslexia, a bit: you have to consciously analyze each word on the page to extract its "reading", rather than just letting your visual cortex pass the words straight into your brain's audio loop.
Seems like it'd be just a matter of developing fluency, the same way as with any other orthography. Adding one new glyph isn't that big a problem for someone who's already likely to be reading texts where long-s is found - so, at least, has been my experience, and while I always hesitate to generalize therefrom, I don't know that it's so unreasonable to consider doing so here.
On the other hand–I'm not sure that someone, who has written an Emacs minor mode to perform automatic ſ-insertion where it is grammatical to do so, is necessarily best placed to speak to the general case here.