Single engine taxi in at AMS 18R always saved me 100kg....Its worth while.
Long term problem is the side-load on the nosewheel assembly caused by continuous nose-wheel steering pressure. Several times a day may save a few kilos of fuel but the unknown is the strain on the NW assembly over a long period of time. This is another example where what was considered good airmanship (two engine taxy) has been conveniently disregarded by the bean-counters.