Thanks for your tests. I do not get the PDF intermediate file, I can only produce it manually.
Inkscape 0.48.4 r9939 (May 20 2013)
ConTeXt 2013.06.07 12:25
I used this code:
\placefigure
[force]
[scatterplot_of_WER_vs_PPL_baseline]
{Scatterplot of WER vs. perplexity (baseline)}
{\externalfigure[/tmp/scatterplot_of_WER_vs_PPL.svg.svg][factor=fit]}
I use it in a big document with all kinds of floats, and this is the last of a 3 graphs with 'force' placement on a row. Also I want to use A3 landscape page dimensions, but now it is fit to an A4 portrait page and that does not work either.