In order to align text vertically in SVG one has to use the dominant-baseline attribute. This has already been discussed on SO (Aligning text in SVG) and is par
dominant-baseline
You could try baseline-shift to see if that works in IE9:
XXX dominant-baseline: auto; XXX XXX dominant-baseline: central XXX XXX baseline-shift: -30% XXX
Firefox doesn't seem to support baseline-shift though, but Webkit and Opera do.