In reply to Foundries that allow font upgrades:
Trinite is a lovely font, but not a general workhouse font like Dante, Documenta, Minion, Dolly, Scala Serif, Baskerville 10, or Sabon Next. It is quirky, like Quadraat, but prettier. It is probably overpriced, but many of the Dutch types are pretty expensive. (and yes, it does not have ligatures, but would benefit from an open type version such as was developed for Lexicon for old style figures, small caps, foreign language options etc.) I have found several instances where trinite is the perfect font. Many of the Adobe (and HF&J) fonts are very good, but I end up seldom using them because there is something else a little better. The ones I use (like Jenson, Bickham script) are not general use fonts.
Trinite:
I am not convinced that TTF/OTF format is a lifetime investment. I remember when bitmap fonts came out that were "high quality", followed by postscript fonts, then multimaster fonts (which were "the thing" if printers could figure out how to use them), then truetype (initially inferior, because cheap fonts came out in that format while the quality fonts were still postscript), then now opentype with optical variants and display and web options, etc. As of January 2013, there are still programs which work much better with standard true type, postscript, or open type. Not all use is with InDesign or Illustrator. There is AutoCAD, help based systems, Maya, Softimage, Media Composer, etc. - and each have their favorite formats. If one wants to convert fonts to outlines and create distortions, the old style postscript fonts are still great. The bottom line, is that it would be good to have upgrade options and reasonable regulations for use (embedded fonts in pdf, etc.) for whatever the next generation of use. I would not be surprised if changes may be developed in font specifications for better epub options in the future.
BTW: here is a response from Underware.nl that is good: "We don't double charge our clients for an OT update. The money previously invested in PS T1 / TTF fonts, will be refunded on the OT fonts. Repurchasing sucks. Never pay twice for the same thing, no?"
A bad response from Fontfont: "Since OpenType is a completely new, different format, the fonts have been revised and the new packages don't really match the old ones, we do not offer an upgrade path"