I've used and taught both methods, and each has advantages and drawbacks. The method of plugging in the neck is actually the older tradition, being used on practically all necked instruments once they gave up carving the whole body and neck from one piece. It requires some skill, sharp tools, and a bit of time, but allows for easy adjustment and repair down the road. In the newer 'solera' method you put in the time making the fixture, but you only have to do it once. After that all the necks will be properly aligned when you pull the guitars off the fixture so long as you're reasonably careful. Carving the heel, putting on the binding, and finishing are a bit harder. Beginning students usually find the solera easier, simply because they lack the tool chops and experience to do a good job of setting a neck and staying within tolerance. I find it hard to get them to take fine enough shavings, partly because they don't stop to sharpen the chisle as often as they should.
Brune's method gets around a lot of that. He has essentially embodied the neck angle feature of the solera in his sanding fixture. The 'floating' tenon is certainly strong enough.
It's also possible to make a removable neck on the solera. You simply make a neck block with the grain aligned with the neck wood, and the usual slipper foot, and plug the neck into it using whatever sort of joint suits your fancy. The trick is to use a removable spacer 2mm thick, or however thick you like to make the sides, when you fit and glue up the neck and block. Once that's assembled you go on with the solera method in the normal way. You do need to remember to cut away the top over the neck joint so that it can be removed later, of course. One advantage of this method is that the surfaces of the slot can be made really smooth, and the slot width exact. You can also 'size' the end grain surfaces of the neck and block that will be inside the slot before assembling the two, and scrape off the excess glue. Plugging in the sides is a real snap. If the neck block is laminated up of the same wood as the heel it's very hard to tell that it's a removable neck.
Last edited by Alan Carruth on Thu May 03, 2018 2:45 pm, edited 1 time in total.