We're really happy with our new double glazing. Not only has it stopped any condensation on the windows, it's made a HUGE difference to the outside noise levels. We have lovely neighbours here in the marina but their heating exhaust is right beside our saloon and it's quite noisy. Not any more though, now we hardly even notice when it's running. The noise reduction also works the other way too, Roger can turn up his electric guitar without disturbing them either.
Although we mainly fitted the DG to reduce the condensation on the windows we've noticed a huge difference in temperature inside the boat. We now only need a very small fire and we've used one full bag of solid fuel less than usual this week. If this carries on it'll pay for itself in fuel savings by the end of the winter.