I have 50w gu-10 bulbs (line) in my living room (Unknown brand bought at Home Depot or something). They are bright enough and they do work well with aperture trim. I also installed 37w Sylvania Tru-Aim IR (12v) in my kitchen, bathroom and dining room. Wow what a difference. Low voltage gives out a nicer light spectrum more comparable to natural daylight. (Not artificial like daylight CFL's). I forked out more for "IR", which has an infrared coating of the bulb, which put out a light like a 50w. They are more energy efficient in that aspect. My understanding is the IR coating traps the IR light inside the bulb and puts out more of the visible light. Cool but way more expensive. I spent days trying to find the cheapest (range of the IR bulbs were $15-$75). I definitely recommend a soft start dimmer, bulbs last forever. I have the Maestro Dimmers. My mother has mr-16 low voltage on a regular switch and they burn out all the time. Hope this help and hopefully my time I spent on research helps. I'm sort of a light bulb/lighting fanatic.

What I have now is low-voltage xenon lights with internal transformers inside each fixture. I'm looking at replacing them because of continual problems, like multiple burned-out bulbs and a burned-out transformer after 16 months, and innards so full of wires and wire nuts that the fixtures pop apart if I removed the glass diffusers (or spontaneously in the case of the smallest strip.) Judging from online reviews, these are common problems with the model that I have. We have line voltage coming out of the walls for the three separate runs of lights, all on the same circuit. If I understand correctly, the electrician can use the existing wiring to install either low-voltage lights with internal transformers (NOT the same brand!) or line-voltage lights. I bought the lights we have based on looks, function, and the showroom salesman's recommendation. Never would have thought to ask to see the inside of the fixture, though.

Thanks for the replies. Yes, I absolutely have a transformer because I bought it myself. It's a 300W Toroidal Magnetic Transformer. It is in the basement below the kitchen. In the kitchen, I have 13 low voltage under-cabinet puck lights. I ran 14/2 romex from the transformer to 4 different locations in the kitchen. From each of the four location, I connected no more than 5 pucks using a terminal block.

Depends on how you want to control them. If all you are doing is turn them on and off, it shouldn't be much of a problem. If you want to dim them, that's where issues start to crop up. Not to be too reductionist or too simplistic here, but most LEDs are solid state electronics, not really technically electrical, and require low voltage DC power, so not only is there a transformer (whether you see it or not), but usually some sort of AC/DC rectifier. Not all electronics behave well to being dimmed with typical rheostat wall switch dimmers. That's also why some LED lights have a slight delay turning on, the electronics. Even if they say they handle 120v and can be dimmed, it doesn't always work as advertised. Depending on why people on these forums recommend the Inspire LEDs (I'm not familiar with them) I would still stick with something either I know or people I respect know. If I want to dim LEDs today, I would buy a whole system that includes the lighting controller—like a Philips HUE system for traditional style light bulbs. LEDs have not been perfected to the point that anything you buy will behave properly. But if none of that matters, just get whatever you want that behaves like you want it (if you don't want the delay in turing on, for instance) Joe