I bought one of these for my Rayburn 8 years ago and it performed just as you would expect a kettle to - it provided hot water!
But, last year I noticed that it was going rusty on the inside around the maximum water level. As they are stainless steel I was somewhat surprised and rang Stellar (they have a 25 year guarantee).
Bless them, they simply said they would send me another one in the next post and that is exactly what they did. Not only that, but it was their steel-bottomed (the other is aluminium) 2.9 lt version with rubber handle - and very nice it is too. And they didn't even want the old one back. Thank you Stellar.
And there is an added bonus - the steel bottom means it heats the water considerably faster. Great.