MIMF

...In short .... are the advantages (if any) conferred worth the extra effort?

For me it's not much extra effort - I can do it without having to think. I can use smaller more available pieces of wood, cut out or hide defects, and get 2 or 3 necks out of one glue-up. I make them from 3 pieces of alder sandwiching 2 strips of walnut, which is not too bad looking. I hear tell it's also potentially more stable than a single piece neck.

Not really much extra work. I made a couple of archtops using Benedetto's book, and his technique of buying flat sawn curly maple 1 inch boards, cutting out three neck profiles, and gluing them together. On a current project, I bought some 2 inch thick curly maple, and had to cut a scarf joint to make the headstock, and it ended up being just as much work. The advantages are that you can use flat sawn wood, and make it quarter sawn, and you can add color variations to the laminations. Also probably much cheaper. Buying big quarter sawn pieces of wood suitable for making necks is pretty expensive.

It is really not that much more effort considering you are making a whole guitar. I always use laminated necks. You can use less wood or smaller dimensions and more importantly, designing the laminates is part of the decorative elements. I view any extra effort just like the effort of choosing/making/installing binding and purfling.

It's kind of funny. One piece maple necks on Fenders are a sign of quality (and some people debate flatsawn vs quartersawn endlessly). Multiple laminate maple necks on vintage archtops are a sign of quality. One piece mahogany necks on some guitars are a sign of quality, scarfed headstocks and stacked heels are a sign of quality on certain classical guitars. I've done them all. I have no idea which is "best", but I do subscribe to the "laminated necks might be more stable, all else considered" point of view. I think two things drive the ultimate choice for hand builders- tradition in the school of building you happen to be building in at the moment, and visual beauty by enhancing the woods chosen. I think cost and minimizing wood waste drove the factories.

Maybe I’m the odd man out here but I don’t really like the look of necks with multiple species laminated together. It creates a ‘racing stripe’ look that, to me, is a visual distraction.

Laminates are great if you can get tight glue joints but there's the rub if you don't have a good jointer and planer. Surface sanders have a terrible time getting you a flat glueing surface unless you spend $20,000 on one. I tend to agree with Andy that the racing stripes are distracting but I think a 3 piece neck is a respectable way to save wood if you want the neck to be quarter sawn. I do like the stripes if they are all tapered proportionally with the neck taper, that's a time-consuming way to do things and it shows some forethought from a design standpoint.

I like to use flat sawn maple (cheap bugger) and laminate a dark veneer as an accent on my neck through guitars. I bury the body section in a quasi hollow body ala Danelectro. I angle both the headstock and the neck to body point.

I really like the look of contrasting color species, and the potentially more stable neck as well.

Attention to the elements of a glue-up can provide a strong, defect free and beautiful piece of material.
Type of wood and similarity of grain/pores
Moisture Content
Grain Direction
Glue Up Orientation
Thickness of Laminates

The advantages of a glue-up still requires attention to selection and orientation..
But selection and orientation become easier with smaller pieces

Time is well spent ensuring fresh, true gluing surfaces.

Don't expect a laminated beam to automatically be stronger..
It introduces more possibilities for error, but most all can be avoided.
Done right, it can always be stronger than one piece.