Chris,
have a look at the Duo2. The current prices are getting so close that the difference in price (between Solo2 and Duo2) is diminishing, especially when you don't need an additional WiFi device....
On a physical level the Duo2 has a built in WiFi, can take 2.5 or 3.5inch HDD and does not need an external power supply.
If you are happy with the existing drive, reuse it.