MSD certainly has some advantages over the stock ignition. The breaker points, condenser, ballast resistor, and nearly 50 year old distributor are removed from the picture. With MSD you also get three sparks in lieu of one (under 3000 RPM), a configurable rev limiter, the ability to readily tune the advance curve at home, a significantly bigger spark, and technical support via an 800 number. On the down side I have read of some complaints regarding component failures but I have not seen any of that. The MSD systems in my cars have worked for years and years.
On the flip side, the stock distributor and ignition work fine. It will need some maintenance due to its age but it gets the job done. I recently spent a lot of time isolating a problem with a vacuum advance module on a stock Pantera. A full MSD swap out would have saved time. But when trying to keep a car original MSD is not an option.