Created attachment 19557 [details]
I'm not sure if it belongs to ps backend.
I got the same result with pdf printing.
I've attached sample ps file.
The html was printed by Firefox 3.0.2 with cairo 1.8.1 trunk.
I changed scale to 100%, 70%, 200%, and unchecked "Ignore Scaling and Shrink To Fit Page Width"
The 100% one looks acceptable.
The 70% one looks strange, there're actually 2 lines, one line with big font type but characters are collapsed, the second line is in quite small font. This might be another bug, perhaps related to css border-bottom: 1px.
For 200%, the font actually is as same as 100% one, just more space between letters.
Created attachment 19558 [details]
Created attachment 19559 [details]
Looks like a Firefox problem. Please file a bug at https://bugzilla.mozilla.org/
The incorrect spacing may be related to this bug: