Regardless of your bias against all the kiddie as well as 30+ hosts who use ControlPanels...but your beliefs are centered around Cpanel....that is not the end of the CP world.

We have used Plesk and DirectAdmin and both allow services/software to be independently custom-compiled, irrespective of whether the CP vendor comes out with a patch or not.

For TMDA...its best to opt for a VPS. The best/preferred ones are from Dinix.com...the cheapest ones seem to be from jvds.com This would be best for an MTA plugin as you require.