I have no problem with compatibility ,my site
www.moonmoonbird.com has worked great with chrome,firefox,opera,safari,and IE11,except some small places need to be improved,and i am struggling with IE browser on window phone about animation and data-binding in styling,everything seems all good.i used many features as i can which provided by polymer,and i use vulcanize to compress my static files and reduce request as much as i can,before used vulcanize my home page has 95 requests ,after compressed,it reduce to only 3 requests.and my site is very fast and less bandwidth,so ,i don't consider it to be a problem which you meet!