Gas central heating is a daft idea for anything other than emergency use.
During a mild winter you'll use roughly a bottle a week (£26), in a bad winter you could be using two or three (£52-73). That's an astonishing amount of money to spend heating a small space like a narrowboat.
On top of that, you have the handling of the gas bottles on a weekly basis to consider, and if you're not local to a supplier, the cost of transport getting them to/from the boat.
My personal preference is a wood/coal stove (full time use in winter) and diesel system for backup/brief morning/evening heating in autumn/spring.
You don't have the old issues of burning red diesel in these small heaters anymore either, as red diesel is now just a dye added to road diesel.
I'm stuck with an Alde heater until I can afford to replace it with a diesel heater. It takes up valuable space in the kitchen, and is too expensive to use. I won't remove it though as it's useful to have as a backup.