"low voltage wiring back to a central transformer." Often a painfully expensive way to do the job. Low voltage requires higher current and low voltage drops in conductors, requiring the use of larger wires. 60 W AC to DC supplies are around $15 each and fit in a single gang box. 120 VAC in one end, 12 VDC out the other. You can cut through the cabinet back, mount a device box flush with the inside of the cabinet back, then use a blank switch-plate on the box. The 12 V lines exit through the bottom side of the box, through the bottom of the cabinet, and then to the nearby lights. Repeat as required. If a single large er transformer fails ALL the lights are out. If a single AC-DC power supply fails all you lose is (up to) 60 W of lights. It works especially well with 20 W pucks. 3 pucks per supply. You can even use another low voltage supply (24 VAC, power limited) with relays to switch the segments. Same sort of scheme as a thermostat, with all the wiring relief these circuits have (and common and inexpensive transformers and relays from the HVAC world). You may need to use as 4x4 box with a single gang plaster ring to fit power supplies and relays.

In consultation with my supplier, I come up with the attached diagram showing my thoughts about wiring the kitchen lighting (part). The green wires are coming from the basement through a wall between the kitchen and a closet. There will be dimmer switches in that wall (two shown). The 110 volt wires then continue up through the wall to a shelf in the closet where the transformers will be located. I was going to put them inside the wall, but my supplier said that that's not allowed. The low voltage wires then continue up through the wall and through the ridge beam and then run along the top of the rafter to a hole drilled through the rafter and down to the monorail track. Question: do I have to put a box on the underside of the rafter, or can there be a tube attached to the rafter through which the wires run? Anyway, the monorail will have two circuits, one with down task lighting and the other with lights shining up to the ceiling. These would be independently controlled. Another, similar, monorail would be over the kitchen counter with a similar pair of lighting circuits. The dimmers and transformers for these circuits are not shown, but would be next to the ones which are shown.

https://www.google.com/patents/US569443 Mr Woods invented the dimmer some 70 years before Lutron came along. Lutron made the modern, more energy efficient version with a diode. There is no advantage I'm aware of except perhaps safety in outdoor applications to low voltage lighting. There are serious disadvantages, like cost and complexity, limited run lengths, need for heavy gauge wires etc. I'd avoid any fixture that doesn't use a normal Edison base screw in bulb. Proprietary or fixed bulb fixtures require you to change the fixture to update your lighting technology. With a screw in bulb it's as easy as changing a light bulb. I expect LED lamps to continue to improve in both light quality and efficiency over the coming decade.

The lights are IC rated and airtight - we have around 35-40 of them on the project. I really don't like the look of surface mounted disc lights and the canless wafer are touted because of their ease of installation, making them less expensive as compared to typical recessed lights with a can/housing. The electrician added the step of installing plastic cover boxes so insulation didn't fall on them when they cut the holes in. I thought there must be a way to eliminate this extra step since they had estimated its cost as $950 for the covers. I was looking for another method and it looks like the tool that RES2 mentioned below would have done the trick. Just wanted to know more about solutions for future client projects. Thank you to everyone for their comments - you've all been very helpful!