Set font for whole file without losing other formatting (in SVG?)

It seems I cannot change the font family globally in all text 
objects in the GUI using the font dialog. It also seems that when 
I change the font family for an individual object through the font 
dialog subscript and size formatting for parts of the text is 
lost. Thus I'm looking to change the font by editing the SVG 
produced by Inkscape in a text editor, but that seems to be more 
complicated than I expected. Upon inspecting the SVG produced by 
Inkscape I see that each `<text>` *and* `<tspan>` element has a 
`style` attribute with comprehensive font style info --- 
essentially all the font formatting properties.  This seems a bit 
wasteful since I use the same font at the same size throughout the 
drawing, only adding the occasional bold weight and some 
subscripts here and there.  It may make little difference given 
the (many) paths in the drawing, but is there any way to set 
things up so that most font properties are inherited from/set once 
in as high a node as possible? I'm looking to change the font face 
used and changing it by search&replace in lots of places --- the 
font name appears twice in each `<text>` or `<tspan>` `style` 
attribute! --- seems like a heavy-handed way to do it.

/bpj