Nice find, John. Just had a quick skimthrough, but too much to digest in work on headphones. I did consider an M1 a while back, especially on the strength of some of the reviews, but it seemed quite pricey for a drop-in, especially as I would ultimately like to sort something out for both my Avalon and my Collings. When I got my L32, I toyed with the idea of a factory-fitted pick-up, but couldn't afford it, nor justify it. However, now I find myself doing a private party next month and having to use magnetic pickups in both guitars. The sound won't be perfect, especially as while one is a decent Fishman Neo humbucker, the other is a cheap Shadow humbucker bought 20 years ago.
I have little doubt that a K&K or a Fender system as installed by Avalon into new guitars would sound better, but, as always, it comes down to Â£Â£Â£ and whether you want to take a 1/2" drill to your end block and risk damage. As far as my Avalon is concerned, I would feel more comfortable about shelling out for a professionally fitted pick-up as Avalon are far more forward-thinking and considerate of musicians in that, as John says, the end-pin requires minimal work to install a jack (Not sure whether this is the same on a Silver. JB??). Why more instrument makers are not so sensible, is beyond me - if you are buying a quality instrument, there is a greater likelihood that you will be a gigging musician and guitars will need to be amplified. (But enough of my rant - just a thumbs up to JB and the guys!)
Conversely, I am very hesitant to take a drill to my Collings. In addition, there is also a split in the Collings owners camp about whether fitting a pick-up and jack actually reduces value should you need to resell. Via other Collings owners, I have become aware of the Vintage 1/8" jack - an option which requires a bespoke cable, but minimises the size of that drill bit. But it's not cheap at around Â£60+ just for the jack and lead, so with whatever pick up you add, that's 50% of the value of your guitar if it's an Avalon Silver.
Another option you might consider is using a condensor mic - if interference from other sound sources is not a problem, then this might work. I have seen Peter Rowan using just one single mic for both guitar and vocals at his solo shows, which sounded wonderful.
I guess what that article says is right, there is no one answer that fits all. Good luck with it, David, and let us all know which route you take and how it goes.