It's largely fine...waiting for the gravity-fed hot water cylinder to refill [EDIT meant reheat] is a bit of a pain if there's lots of hot water use, but other than that not much is wrong. That said, that cylinder and the loft tanks are also ancient, so presumably heading for EOL, so if...
Our regular boiler (25 years) seems to have started coming to the end of its life (suddenly having problems, last servicer emphatic that getting spare parts is now/would be a serious pain) etc. so we're looking to replace it. Two tanks in the roof, a vented cylinder upstairs, 17 radiators, and...