Probably not
The output of LED bulbs of a given wattage seems to vary considerably but a 35W halogen produces around 5-600 lumens where a 5W LED would probably be around 400 lumens.
The very best may just approach the performance of the halogen.
That said, I'm in the process of replacing the halogens here at home (we have about 50 of the things) and our rooms are over-illuminated IMO (three rooms currently have more than 10 50W halogens) so replacing them with LEDs of slightly lower output isn't a probelm
Have you calculated how long it will take to make this pay?
I was wondering.
I just replaced 5 x 35w halogens with 5 x 7.5w LEDs.
Difference is 137.5w.
Burning 4 hours/ day that's 550w.hrs , 0.55kw.hrs.
That's about 7p/day saved.
the bulbs cost £19.50 EACH £97.50 TOTAL.
It will take 1393 days to pay off the cost. of the bulbs, assuming I don't break one.
But.
The existing fittings would not take an LED GU10 bulb, because the shape is non standard.
So add another £60 for fittings.
£157.50
At 7p per day, that's 2250 days -over 6 years- to pay off the cost.
Plus, the original 5 35 watt bulbs cost about another £10, but we'll forget that.
Changing
fittings can be an unexpected- and unadvertised additional cost.