We are now living well with it parallel 1x 50W halogen and 1x this LED, see photo. Links 50W halogen, right 6W LED.
Another thing you can use the lamp with both DC and AC with transformer. Have only a 15W LED transformer tested and ultimately to serve the 50W bulb can use the old transformer.
Addendum 03.11.2015: due to the size issue, I have 2 photos taken but can not subsequently upload. The dimensions are, diameter 20 mm, length approx 32 mm, respectively rounded.