Re: Halogens don't like dimmers?
Rubbish! Tungsten Halogens on dimmers are absolutely fine.
They're only warm enough for the tungsten to evaporate once they're already hot enough for the halogen cycle to run. These are a pretty big part of my day job, we'd notice this!
Domestic ones are even better as the actual halogen capsule is tiny, protected inside the outer envelope so stays clean and loses less heat to the environment.
Also - run them at 90% and you increase the lifetime by around 30% with a small drop in brightness, equally, run them at 110% and the lifetime drops by about 30-50% (with a bit of a brightness boost).
Overvolting is pretty common in the UK - many lamps sold in the UK and Europe are 230V (or even 220V). In the UK, your actual mains voltage is usually 240V, sometimes (eg most of Central London) as high as 250V.
- This is also why a lot of CFLs and LED lamps are awful. They're just not designed for the mains voltage we actually have.
Flashing may kill them, but that's thermal shock snapping the supports or filament, not evaporation.
So dimmer switches can be better - soft start, can run them at the actual rated (RMS) voltage, and the option to run at 90%.
That said - GU10s are fragile as heck. Choose MR16 if you can, they last considerably longer. Low voltage halogen is also more efficacious than mains voltage of the same wattage, which is nice!