Re: TCO?
My kitchen is now lit entirely by 7.5W (50W equivalent) 480 lumen GU10 LEDs fitted with diffusers, replacing 50W 900 lumen halogens. The light from the LEDs is less directional, has a nicer quality to it (seems 'whiter') and the entire kitchen feels more brightly lit overall despite, apparently, having half the lumens I had before.
I bought a pack of 4 when they were on special offer at B&Q and the £10 investment seemed worthwhile as a suck-it-and-see given I'd ran out of 'spare' halogens, it seemed like an ideal opportunity to make the switch.