I have had the message “lower than expected” every time since I switched but am not sure it is right. I will know in time I suppose. It may take you a long time for running cost savings to cover the cost of a BG installation! My boiler is 21 years old. It will have to be replaced one day, but I will wait until it packs up. Then sadly it will not just mean a new boiler (probably an Intergas one) but new radiators.