Electronic Ignition?

I am using a Boyer points assist unit on my 99 with 18d2.Good strong spark ,Still have to ocasionaly adjust points . Simple to time and maintain. Cheap to buy.  I also use a similar one from Pazon on another machine.  I have tried to fit similar system to the powerspark  but could not get it to work on the 99.  No idea why , but in retrospect would not want to have to mess with timing disc and strobe . Did not find the sellers much use either. Others may have had better luck.

Lionel.  I use a Boyer micro in my 18D2 distributor on my dommi.  The distributor needed slightly modifying (dead easy) and this electronic ignition does away with the rubbishy advance and retard, but it's nearly 4 times the price of the one you've listed!

If your advance/retard works well, then this seems like an excellent option and certain worth a punt.

If you go for the Powerspark check that it does not make your rotor arm hit the cap. I would also insist that they agree to a full refund if you are not satisfied (for whatever reason)..You may have to fork out for new carbon leads ,plug caps coil and dump the 2MC ! Somewhere in that lot is the reason I could not get it to work.  The Boyer box just worked with no issues. Powerspark in the junk box.

... Boyer points assist system on a unit Triumph 500 and it worked well. I fitted a switch to allow it to revert to conventional points and it idled faster and more smoothly with the Boyer system.

Another option, I make and sell an 18D2 kit based on Boyer Bransden parts and amplifier. This does away with the advance/retard mechanical mechanism and the rotor gubbins (and the cows udder) you can fit the 18D1 cap. This does need 12V and twin coils but then you have removed any variation in timing between the two cylinders. But the 18D2 is not modified. (can be returned to original if you really must)

It was a Powerspark. I made 3 or 4 attempts to fit it over some months, Going back to the points between attempts.Sent it back twice at my costs to be checked . They sent me a damaged 2nd hand one back. I had to modify it to fit .They refused to refund. When I asked about Dwell time for coil saturation ,they said it was "a sort of magic" , Pathetic.  Waste of time talking to them. The problem could have been just not compatible with something on my bike.  The Boyer worked ,no issues at all, if there were issues Mr Boyer would have sorted them.

Will ultimately come down to how much you intend to use it. If your plan is a LOT of miles each year and/or you really don't like 'tinkering', then electronic is the way to go as it is fit and forget. If you are only going to do 500 miles, then you might as well stay with the points set-up and check it once a year. Set properly, and providing the dizzy is in reasonable condition (and electronic won't necessarily cure that if it isn't) the points gap and timing check should be ok for 1000 miles at a time, probably even longer with a points assist unit as mentioned by others.

Me? When I got my Norton 22 years ago, the mag on it wasn't the correct one (manual advance) and was dead. The cost of another mag and reconditioning it made the Boyer equipped 'mushroom' a bargain. Add into the equation that I knew nothing about mags if they went wrong whereas I did/do about electronic controlled sparks, it was for me a no brainer. It's still there and starting is usually first kick.

At the end of the day, it is your money and choice, but Roberts comments would make me steer away from the one you mentioned at the beginning.

Over the years I have had many EI  systems on cars and bikes .They always made the spark better  often just a stronger spark compensated for other issues and made a rough hard to start old banger  with a half dead battery start instantly and purr.  Getting rid of points is a big plus. I have always thought that there is a trade off though. The early Boyer fitted to the "Mushroom" on an atlas made it far easier to start but Killed a lot of the low speed urge with its slow advance curve and made timing  more difficult. Strangely it does not suffer the usual kickback with a low battery (2MC helping?). A Pazon assist unit made a stupidly race tuned Ducati just about usable on the road ,firing up well and smoothing out holes in the carburation.The 99 with Boyer assist will fire up first kick ,very helpful with spine problems. I had hoped the Powerspark would see the points off. But in the end riding was more important than fiddling and frustration.