High Efficiency Condensing Boiler

My old gas boiler has given up and had a guy survey our requirements today.His
recommendation is for a HE Condensing Boiler which is apparently very efficient-but he did point out that there would be a lot of steam-and he stressed-a lot- from the flue which would be at the side of the house-and suggested that this might create a problem with my immediate neighbour.
There is a less efficient boiler which creates less steam and this is an option.

My question is to anyone who knows or has these boilers-is it a big problem?
Should I opt for the less efficient one?

Your question might have been answered already, but yes, I have one since a few years. They do steam, about what one would see when the kettle is turned on and kept boiling. But it depends also on what power setting/demand it is running. The more output power it creates the more it steams.