We are looking to retrofit our house lot of 50W MR16 12v Halogens with 5w MR16 LED's. We have one electronic transformer per light which have a minimum loading wattage of 20w, Specs of the transformers are below 

http://www.mercateo.com/p/721-33938604/NOBILE_EN_60M_Transformator_60VA.html

I have changed over 4 or 5 of them so far and they seem to be working ok, but i am concerned about the wattage on each transformer being below the minimum loading. If the lights work, is there still a potential risk in under loading the transformers? We do not have dimmer switches by the way.

If there is, i will bite the bullet and switch each light over to 240v GU10's, but there is no point doing this if not needed

Thanks