Comment 6 for bug 179679

This is getting off-topic, but I did some research and found out what the CDATA is:
"If you save an SVG file from Illustrator with the "Preserve Illustrator Editing Capabilities" checkbox selected, Illustrator writes out what amounts to an embedded native .ai file in the SVG. When Illustrator reads the SVG file back in, it sees this embedded information and reads it instead of the SVG content.

You can see the embedded editing information by opening the SVG file in a text editor and scrolling to the end of the file while looking for "<i:pgf". If you delete the entire <i:pgf ...> node, Illustrator will read the SVG data and you'll see the Adobe Server changes. (The ... represents the enclosed .ai info.) This also makes the file smaller making it process faster in Adobe Server."

Hence you break AI compatibility by leaving the <i:pgf tag but removing the CDATA tag around the binary data.

Compare the attached file with the 1st file attachment above (2 inkscape logo-illustrator test.svg). The only difference is I unticked the default option to preserve editing capability.

Sorry, I haven't checked if there's a bug report relating to the <i:pgf and CDATA tag, or Illustrator compatibility. I will open one if you wish.