I have to disagree. Designers who can actually write serious code are rare unicorns and can typically demand a higher salary because of it. I wouldn't downplay my design skills (if I had any). I'm not sure what your pay grade is at the moment, but an engineer that can design is worth more than someone who is solely a designer or engineer in my books. Maybe it depends on the size/type of company? A small-ish company or startup would be more likely to value someone with multiple toolsets, whereas larger companies look more for specialists.