I've been down the road using custom CMS's and they never quite worked out so that's why I switched to Wordpress. The designers were either too expensive, too flaky or both.
What use to cost me $500 a pop can now be downloaded as a free plugin.
I'm not knocking all designers, I'm just speaking from my experience over the past 7+ years of running a paysite. I can't tell you how many thousands of dollars I spent over the years before finally switching to Wordpress and I couldn't be happier.
To add insult to injury, I paid an SEO company $1,200/month for a year to do something that Wordpress took care of in a few months. There's a reason why the following companies are using Wordpress...it works!
http://www.wpbeginner.com/showcase/2...ing-wordpress/