Im quite partial to a firebird now!
i have a warmflow at home which is fine.
firebirds have the burner in the middle, can get to all the connections without fuss.
Firebirds are good boilers in my humble opinion. I had one in my old house, and the poor thing never got serviced, reguarly sucked up the dreggs of the tank, and pump cruddy sludge round the heating system. Typical plumbers house!
I put a new system in the current house, so I've taken care of the boiler from day dot.