Had issues with Xara and ecwid e-commerce not playing well together. Had to find an alternate (I still use Xara most often) that played well with ecwid. I choose WYSIWYG Web Builder, WWB. It offers responsive but allows you to design breakpoint (variants) that you can customize layout for a particular size. A bit of the design control from Xara variants plus responsiveness. The last few WWB sites I built I used Xara to prototype for the customer. Xara is just so much faster. I do wish Xara could figure out how to implement better responsive design AND address the issue with add ins like ecwid.