The tank looks O.K but it should've been made to hold 40 litres of fuel. I doubt anyone who owns an Adventure would stump up £650 for an extra 5 litres of fuel capacity.
If I was kitting up my bike, I'd rather spend the extra for the Touratech tank because of its larger capacity. If this tank was 40 litres and £ 650, they would have had a real winner on their hands.