I saw this previewed at SEMA in 2011 when I was there with my business. I also talked to FAST and Holley. Their systems are very good but what I liked about MSD was the lack of wiring needed to be hooked up. The body of the EFI has the MAP & MAS along with the throttle position sensor built in.
MSD says you can run the system without running a return line for fuel. That was also a selling point. BUT!!! after reading up on the Atomic efi site, I found that you can have cavitation bubble occur in the line if you run with no return.
As I was building the car, I already knew I was going to go to FI down the road but didn't know which one at the time. So when I had the new gas tank made I had an extra bung welded in for a return and also welded brackets on the frame for a return.
I also went on youtube to watch Steve Maganante do the change from a carb to MSD to see what I will have to do.
Lastly..........I have had much good luck with MSD thru the years and have their starter, distributor and coil on the car now so I figured stick with a company that has been so good so far.