Thinking of Upgrading from ReadyNAS Duo - Best options?

This is the age old question when needing something a bit larger or faster. Which one, and which path is the most effective in the long term. I faced this a little over a year ago and finally decided on the NVX (32 bit Intel processor discontinued in favor of the Ultra 4 with 64 bit processor) and have not regretted it. Actually while copying over the files across your network will take some time, the built in backup routines make it almost a set it, start it, go do something else and forget process.

The Ultra 4 with an Atom D410 processor (single core), 1GB of memory and diskless is #403.02 (sorry no UK pound symbol on my US keyboard) while the Ultra 4 Plus with the D510 processor (dual core) is #450.10 and the Pro 4 (same hardware as the Ultra 4 Plus) is #499.18. The advantage of the Pro 4 over the Ultra 4 Plus are the business features that cannot be added such as Active Directory, rsysnc over SSH and a few others, along with a 5 year warranty (the Ultras have a 3 year warranty). Note: Prices are as posted on Scan.co.uk.