I agree.. another advantage one has along with the size, less power used factor would be the weight factor.. 120 grams compared to 1,120 grams of weight of the Passport.
it draws a fourth of the power a 2.5" (Laptop HD) consumes, from this one can imagine how much a 3.5" would use if compared.
Its easily stuffable into any dashboard compartment's to be used as a usb drive on pre's, or consoles or on any usb compatible device in hand.. a Passport on the other hand wouldn't be that easily manageable, due to its weight, size and power consumption characteristics.
Dimensions of the DeQuan (Spinstar N2)
Height: 86.5mm
Length: 56mm
Width: 10.5mm
Weight: 120 grams
Dimensions of the Passport (WD)
Height: 166 mm
Length: 137 mm
Width: 54 mm
Weight: 1130 grams (1.13kg)
http://www.westerndigital.com/en/products/products.asp?driveid=352&language=en