From the perspective of the energy saver

The lamps are perfectly packaged, could easily be replaced with halogen lamps G9. The luminosity is the same as the 28 watt halogen lamps.
So mathematically saves 25 watts per lamp built. the converted approx 3.40 euros costs.
A kilowatt-hour costs 25 cents, thereby saving the lamp in 40 hours 25 Cent energy costs.
The cost of the lamp are thus saved after 544 hours.
With daily turn-of - with me in this particular case - 5 Stunden profitable replacement of lamps is, after nearly 4 months. Added to this is the expected service life and hence the cost of lamp replacement. This is my experience with halogen lamps more than 10 times shorter. So there are extra 10 replacement bulbs that I save.
If my calculation is correct, then you have to replace as soon as possible 28 watt halogen lamp for cost reasons each G9.