Comparative Performance - Two Bay
Competition for the NAS-2 is tougher because there are a lot more low-cost two-bay products than four-bay. Filtering the NAS Ranker for two drive products and sorting by ascending price finds the diskless model STCT100 NAS-2 as the 11th least expensive at $200.
To make things worse, the NAS-2's #44 performance rank is bested by five lower cost products including Synology's DS214se (#29 rank / $153) and Thecus' N2310 (#30 rank / $143). Looking at the Ranker Performance Summary detail below reveals sub-ranks that aren't really that bad. But, simply put, the NAS-2 has much more competition in its class and just isn't as good a deal as the NAS-4 is among its smaller comparison group.
For the NAS-2, buying diskless is again the way to go, although at current prices you save only $60 if my calculations are correct. Since Seagate is still ramping up production, however, I'd expect the diskful model prices for both the NAS-2 and -4 to start heading down soon.
Ranker Performance Summary - two bay
Seagate's past runs at gaining NAS market share haven't measured up in performance or features, but have generally been priced attractively. But new product introductions haven't kept pace with the competition, so Seagate has pretty much been off the radar of most serious NAS buyers.
The NAS-2 and NAS-4 have a shot at changing this. They have competitive feature sets desired by both home and small-biz buyers, are reasonably quiet, power efficient and come in diskless versions desired by savvier buyers. Once high current diskful model pricing gets adjusted to reflect market reality, the NAS-2 and -4 should retain Seagate's traditional good-value pricing. (Diskless models are already there.) Bottom line, they're definitely worth your consideration.