I used MS on two very different engines. I fabricated the harness for both of them. Read the instructions carefully, and you won't have too many problems. Building it yourself allows you to run the wires where you want them, and you can put connectors where it makes sense for easy maintenance.
I found it easy to tune, and the software is very easy to work with. You can get 90-95% of the tune done just by driving around. But getting it on a chassis dyno with a good tuner for that last 5-10% will really make a difference in drivability. Once tuned, you really don't ever have to touch them again.
One of them went on this engine; 427W stroker, huge cam, IR induction, and flex fuel. I eventually got rid of the distributer, and used a crank trigger with a coil pack.
The other one went on this LS6. Pretty calm engine, running E85, only run on the race track.
The rumpy idle mostly comes from cam choice, and not intake choice. Once properly tuned, port injection will manage a radical cam like it's a little kitten.