Hi Junglerott, and welcome to the board. I don't have much experience with adding cream to milk, other than the monterey jacks that I make from the recipe posted here, only I think that I end up added a little more cream than recommended. On top of that I use whole raw milk, so the cream content in that is fairly high by the end. After pressing overnight it is then left to dry for three days at room temp before putting in the cave for another 2-4 months to age. Daytime temps have been around 20c and so far I have not noticed any off flavours or smells, and the end cheese is not strong or harsh.
I have also made cream cheese from pure cream, and the culture was left to set at room temp for 15 hours, and it drained at room temp for another 24 hours, and the end result was beautiful.
I think that is must be remembered that cheese IS milk fat, so the adding of extra shouldn't make that much of a difference as different milks have different cream contents anyway. As Cheese Head said, if we have used the correct procedures, ie: cooking temp, culture, rennent, sterilizing etc, then I would think that it should be alright. I do agree though, that the end cheese might be softer and of a different texture than a cheese with a lower cream content.
Again, the above is just what I have learnt from my own experiences.