I don't know what sheba or gourmet fillets are like, but would agree that NM is sort of supermeat texture. It's like a coarse pate but it does have pieces of meat in it.
Helen - you might find that once you've had the boys neutered it won't be long before they're ready for adult food. I think kitten food is good while they're growing fast but I've never kept a cat on kitten food until 12 months. After all, there's not a special kitten mouse in the wild is there! Jaffa and Magpie went onto adult wet food at about 9-10 months, but I kept them on kitten dry for a bit longer. with Mosi I felt that he was ready for adult by 7 months - he was looking a bit chubby. Might have just been the way he was growing (he's always tended to grow up so that he was tall and lanky, and then outwards) but I decided to put him onto adult at about 8 months.