I know they are no longer making the Marista range of products, from their reply to my email, it is basically a case of what is left in stock. Although they gave me alternatives for my Carpet solution.
We were struggling with a porch for our maritsa 700.. managed to find a solution hopefully..
just bought a vango calisto 500 for a smaller weekend tent.. we also got the calisto 500 porch.. which measures 320cm wide and 205cm tall and adds approx 180cm on the front..
As the front of the maritsa is 320 wide and 200 high I think it will fit pretty well..
Trying the new tent out at the end of April then will try the porch out on the maritsa at the end of may..
We have a coleman de gamma 5 extension and are going to try it on our maritsa 700 hopefully at the weekend as long as the weather stays dry. I will let you know if that works we have been trying to get a porch since before Christmas and someone on here recommended this one as the measurements are nearly the same.