After realizing that there was something strange about the text size in my inkscape designs I followed the bugs associated (#168151, #168164, #168344, #170099 - some of them seem to be duplicates) and there I noticed that the text size in inkscape is expressed in pixels, but the dialog doesn't inform that.
I wrote that a couple of days ago, but I was wrong. Type isn't expressed in pixels. It took me a while to get it, but now I understand. The size is expressed in a unit that is 1/90th of an inch (corresponding to the default inkscape resolution of 90 dpi). That can be just right for svg and on-screen presentation, but for print those typographic size units are quite misleading. Regular users are used to typographic points, which are in DTP equal to 1/72th of an inch. The current units are only used in inkscape (ok, maybe they're the default units for svg but they have not much use for print). The problem of having these units is that an average user won't get what he/she expects. This is, imo, a critic usability issue. It's not intuitive, the result isn't what a regular user would expect and it forces the user to calculate the size (and forces to realize how, because there are no clue of what units are used in the UI). I think this issue should be marked as critic.
Meanwhile, for everyone looking for typographic points in inkscape, there's a kind of workaround. Multiply the desired value by 1.25 and you'll get a equivalent size. (example: if you need 10pt type, then use 12.5 units)
Regards, Gez.