The QNAP TS-431P2 is an interesting network drive if you want good performance but don't want to spend a huge amount of money. The Annapurna Labs processor is able to fill a gigabit connection properly. If you really put a heavy load on it, you will notice that this is not a top-class chip.
The TS-431P2 is available with 1 or 4GB of memory on board. It sounds crazy, but we would advise you to buy the cheapest. If you need more memory, you can always upgrade yourself. We do recommend an upgrade, because then apps run more smoothly and you can also use the Qsirch search tool. You have to screw a little bit for that upgrade, but you can save some money. You could also make the step to 8 GB of memory. Do that only if your tasks are really heavy require a lot of memory. To be quite honest, you probably require a NAS with a more powerful processor in that case.
All in all, the TS-431P2 is a smart choice if you are looking for a NAS. With a price of 400 dollars, the 1 GB version is also quite reasonably priced and, as far as we are concerned, that is the most interesting choice. It is eligible for a Great Value Award, but it is not the variant that we tested. We think the 4 GB version is too expensive.