The mh will be more intense. I'm not real sure what the question is, cause all the answers I'm coming up with are pretty samrtassed answers, LOL. FWIW, with 20K MH, you do not need actinic supplamentation, it provides alot of light in the same wave length as actinic.
The 20K will have several different peaks and provide the same peaks as actinics do, FWIW, I am about to upgrade my lighting and will be going with 20K, I plan on using my actinics as well. We'll see how blue it is and then revise from there, LOL.