Ok, thought I'll give ImageMagick a try and then worry about convincing my webhost to install it.
And there, I run into a problem with parsing of svg: when reading an svg which has a viewbox set to a portion of the entire image, ImageMagick renders only the top left corner of the whole image.

Is there any known issue with ImageMagick not being able to analyze the svg viewBox correctly ? Note that I get same result with command line convert and Image Display just displays a blank image.
I know it's more a question for image magick forum but it doesn't seem to be as reactve as this one...