"Dwell is an electronic term that has to do with how long current is supplied to the coil primary windings. An increase in dwell increases the magnetic field inside the coil's primary windings. The coil only puts out a spark when the magnetic field collapses. The stronger the magnetic field when it collapses, the more energy is created in the coil's secondary windings and the more energy is in the spark.
This is only important if the spark energy is marginal to jump the spark plug gap. More energy than is required to jump the spark plug gap and ignite the fuel air charge doesn't accomplish anything but use more electrical energy and create heat.
On top of that, creating a magnetic field takes time, as does the collapse of that magnetic field. Increase the dwell too much and the magnetic field doesn't have enough time to rebuild at high RPMS."
I think this translates into "The brand of TFI if it is working properly doesn't make much difference"