IMO, reflowing text is big advantage if you're going for "portability accross screen sizes".
It's a big advantage of your content is all pretty simple text; it's less useful for any other content. For complex content, you really need human attention to size-specific layout to getting anything better than just zooming content designed for one size.
In some cases this can be fixed by cutting the margins, but aside from a certain unpleasantness I feel reading an almost-marginless document, it's often still not enough to comfortably read.
So for the most part, whenever possible, I go for ePub documents using Marvin (also an excellent app), and I print the larger documents.
It's one of the main reasons I'm considering getting a normal-sized iPad though.
Does anyone here have a similar experience for that use case ? An iPad Pro seems large enough, but I don't really know. I've seen the Sony dpt-s2, but it seems very expensive given its limitations.
Most of the people will agree with me that straining your eyes is not a good solution ;) Little letters are not comfortable neither healthy.
I tend to keep a whole bunch of things I want to 'read later' in my iBooks collection, just save as PDF and transfer to phone, or if already a PDF just download it directly; zooms great too. I got all kinds of device manuals, but also PADI and other diving reference books; always good to quickly check up on it when in doubt and then to reinforce that information with the knowledge of your dive buddy.
Indeed, for content that does not really need a layout outside of some headers (<h1>) and paragraphs (<p>) HTML is perfectly fine.
Quite a few text portions of conference papers (read: Tex :) can be rendered as markdown and then easily converted to HTML, but it won't feel 'as well', thus PDF is a easier format that also reflects the original intent and format.
IETF RFCs typically can be rendered in a myriad of ways thanks to xml2rfc, then again, one mostly will end up reading them from tools.ietf.org or to keep local, render as PDF and load it into iBooks.