The timed vs 24/7 heating question again

bsod

if the room with stat drops below 12 degrees, you're wasting money heating it whilst asleep, before it was off for 8 hours, now it could be off, could be on.

The is it condensing or not argument is largely irrelevant, you have little or no control over the return temp, the often over emphasized efficiency gains from newer boilers come largely from better heat exchangers.

On top of that, the weather is different, the temps are different, the times are different, the boiler is different.

If you're saying that the boiler fires constantly regardless of thermostat setting, then that is clearly going to result in increased gas use.