As marketeer I'm not the decision maker within our agency, far from. However I am often asked to review or trial a new package or tool. With Litmus, the biggest leverage given from our team was based on the practical advantage. "No more need to consider buying various phones, tablets and whatever."- in general as agency I feel we focus on cutting costly time. Reaching a buy-in must have the requirement of a low learning curve (unless extremely specialist tool), practical and reliable. if it costs unnecessary time trying to work a tool, it will create time gaps and ultimately cash in.
We have a great team of decision makers that feel if it saves us time and hassle, it's the right tool. Sometimes this means the tool can be simple and maybe not as ultra-featured as long as it is smooth.
Litmus builder link is not functioning. Is there another way for you to attach the code you have used so we can find the issue for you? Generally with use of color, check if you have everything on inline-css and not in a style in header. Also make sure your code exists of 6 figures (#000000, NOT #000!)