My experience with Tri-Spark is that it is the best thing ever on the Trident, but I am not so sure with the Norton units. I dont have one fitted to my Norton, am quite happy with my RITA, but I have two BSA B44 Victors to which I had Tri-Sparks fitted.
One of the Victors has two spark plugs and therefore twin coils so should be exactly the same as a Commando as far as my Tri-Spark is aware. This bike has gotten through about four Tri-Sparks which the manufacturer has always replaced, I had gone so far to put a traditional Zenor Diode on which I am told is quicker at dampening electrical spikes than my Podronics, I also fitted a 1 ohm resister to the feed in case the unit was getting too much power.
The last time I ran this bike the Tri-Spark ran for 3 miles before getting rather rough and failing completely by 6 miles, fitted the spare Tri-Spark I always carry which cured the problem but only for 1/2 mile when that unit failed.
I have fitted Boyer back to that bike which now runs flawlessly.
My other Victor is standard. Both the units that failed on the other Victor work fine on this Victor for some reason, but I have to say I do not like the timing curve.
If I set the timing so the bike goes fastest at high revs, the ignition is far too advanced at low revs just off tickover so I get a knocky but not pinking engine, if I retard the ignition so that its fine at the lower revs, I lose a lot of power at higher revs.
I would be interested to know how you guys find such on your Commandos.
I now have three of these units but will probably soon end up using none of them.