...bettter yet, whose idea was it to put the distributor on the back of the engine. Setting the dwell is easy. If you have to change or file points, adjust point contact alignment, etc. depending on how well you like lying on top of the motor.....or you get very good at removing the distributor, making the adjustments and reinstalling it. Back in the day, I thought all of this was fun. Today, I don't have any desire to ever adjust a set of points again.
Changed to the Pertronix about 3 yrs ago and it has worked fine. No problem with the tach or anything else. Like John said, it is simply an electronic on / off switch that replaces a mechanical on / off switch (points open or closed) that was there originally. For me, it was simply a decision to replace a mechanical system which will wear with an electronic component which hopefully will last the lifetime of the car - and of course that is an unknown - electronic components are obviously not immune to failure.