I am in the process of migrating an internal site from HTTPS to HTTP. Once the change is made across the servers will the clients automatically detect and connect using HTTP? My biggest concern is having to re-install the client throughout the environment.

I've only done this once.  But, if I recall correctly, it does require a client reinstall.

Here is a post that describes the key concepts for client computer communication:

http://blogs.technet.com/b/configmgrteam/archive/2012/05/25/system-center-2012-configuration-manager-r-i-p-native-mode.aspx

Key concepts for client computer communication:

• Client computer communication is about securing end points. The two end points in this case are the client and the site system roles that the client talks to.
• A client can communicate by using either the HTTP or HTTPS protocol. HTTPS requires the client and site system roles to be configured with valid PKI certificates for mutual authentication.
• Intelligent client behavior:  This enables the client to select the most secure communication option available:
  1. If the client is configured with a valid PKI certificate and there are HTTPS site system roles available, the client uses HTTPS.
  2. If the client is configured with a valid PKI certificate and there are NO HTTPS site system roles available and the client is configured to use HTTP, the client uses HTTP to communicate with site system roles.

Just to validate what Tom posted - the clients do indeed auto discover the change and update accordingly. I did have to re-install the MP role on my primary but everything is looking good!

Ah.  I think I was thinking of switching from PKI to self signed certs.