Migrating from Server running 2008 r2 to 2012 r2 Ran adprep and then had to back out

We have a Dell Server running server 2008 r2.  Active Directory and DNS roles are installed and running.  We are running an EMR software and are running out of space.  We purchased another Dell Server that has Windows Server 2012 r2 installed.  

I started the process to migrate the Active Directory Domain Controller and then was told not to by the EMR software company Tech.  Here are the steps I took.

I ran adprep /forestprep using the windows server 2012 disk. Schema version changed successfully.

joined the 2k12 as a member server by adding the Active Directory Domain Services role along with the required features. no problem.

promoted the server to a domain controller.  added to existing domain.

check on dns server and global catalog and replicated from the 2k8 server

rebooted then verified server was added to domain controllers, dns name servers, and is listed under servers in active directory site and services.

Transferred the FSMO roles.

I stopped here and then allowed the programmers to begin migrating their software.  They noticed the roles and asked me to remove them.  they said it would affect performance.  I told them the server we are migrating from has those roles and is running their software but they were adamant that I remove them.

So basically I transferred the FSMO roles back to 2k8 server and removed the DNS and Active Directory roles from 2k12.  I am going to leave the 2k8 server as the domain controller/DNS server.  When they move their software my disk space will be a non issue.

What about the schema change?  Can I leave it as is or do I have to restore the system from backup?  Are there any other potential problems I need to consider?

Thanks in advance