Thank you for your comments, suggestions and support
I have just recieved my Duo and I have to say that it greatly exceeds my expectations. So far the stove has outperformed its spec. both in terms of boiling times and fuel consumption which is contrary to most other stove manufacturers claims.
I am interested in the new filler screw and the smaller bottle. Fuel economy is so good that I will rarely need the 500 ml bottle. Please could you let me know the cost of both including shipping to the U.K.
I do hope that you manage to solve the simmering problem, that would really make it the stove of stoves! Although I hope you manage to solve it without necessitating buying a completely new stove.