I use myself both GU10 and MR16 bi-pin (low voltage) LED replacements for what should be Halogen bulbs.
If you need the amount of light that you get now from the 50W bulbs, then no. This will not cut it.
But do you?
I have 6 GU10, 3W each LED that go on a fixture designed for 6 35W Halogen. For dinner, that is all I need. Yes, it is on the romantic side, but since you have 6, you can point 3 at the table and 3 at the walls around and you have both decent task light and ambient light.
Add to that the fact that there is the option (almost always)to add more ambient light (add the 3 LED above the bar next to the dining table, or the 2 wall lights in the hall next to it) and you are just fine.
In my kitchen, I have 12W LED recessed lights which replace 65W equivalent and they give PLENTY of light. you can do brain surgery under that light... So really, people give LED bad rap. They do great job if you get the right light for the right setting and make sure to get the right amount of Lumens.
The W per Lumen ratio is great, and light quality is great. It only fails when people don't realize that the things they buy, even though it should be clear based on the data on the package, are too weak to replace the incandescent bulb. a 3W LED cannot replace a 50W Halogen is the short answer, but LED CAN replace Halogen if you plan it right.