I like the look of the Squid Spahetti. But I've never quite understood the need to add water from the pasta cooking, especially as you have reduced down the tomato sauce?
Nigella's Squid Spaghetti (from NIGELLISSIMA) is a tomato-based seafood sauce for pasta. Once the spaghetti has cooked it is added to the pan of sauce, so that the spaghetti can soak up some of the flavour and become coated in the tomato base. This is the traditional way of combining pasta and sauce.
A little pasta cooking water is added to the sauce as this water contains some starch from the cooked pasta. The starch helps the sauce to stay emulsified and also helps the sauce to cling to the pasta. If the sauce becomes too thick once the pasta has been added then you can always add some extra cooking water to thin the sauce back to the correct consistency.