Question for your JS folks: How are they going to handle document.write calls in third party or even 1st party tags ? Those are blocking by nature and trying to load them up asynchronously will ruin the page. I know there are a few document.write overrides but I'm interested in seeing how they would approach this :)
I'm the founder of UberTags, which is a similar solution. We automatically transform doc.writes to appends to handle async. I'm assuming GTM does something similar.
