Unfortunately, SVG does not support bilinear color fills. Therefore, the convertion of Matlab patches is not straight forward. In addition, figures with patches generally contain a large number of elements. This puts some restriction on the usage of overlays to emulate a bilinear shading. The usage of color filters is inadequate due to speed limitations.
Using images in matlab plots can offer some advantages as the pixel graphics is highly compressed. The axis elements are still vector elements. This combination is good for publications as font styles and labels can be reworked at any time.