On the Original Drake (CST744E or CST744S), the 1.28 tank (ST743E) and the 1.6 tank (ST743S) look the same with different guts. There is also a new-look tank in the 1.28 that is an option (ST743EN).
In the Drake II, which is what you have, the 1G tank looks noticeably-different than the 1.28gpf tank.
CST454CUFG toilet, with the 1G tank (ST453U), is shown in the photo directly below:
TOTO CST454CUFG Drake 1G
CST454CEFG toilet is shown in the picture directly below, with the 1.28gpf tank (ST454E). [For what it's worth, that same ST454E tank goes on the Vespin II skirted toilet, which is 1.28gpf; the box for the ST454E tank will say DRAKE II/VESPIN II TANK on it]. At least one supplier got confused with a member's order because his sheet called the ST454E the "Vespin II Tank" and so he ordered the "Drake II 1G" tank instead. That may be what happened here.
As to performance, the reviews I have seen of the 1G are actually very positive. HOWEVER, one must understand that a person who knowingly purchases a 1G toilet is doing so because they are interested in helping the environment and water saving is important to them; accordingly, they are likely to be happy if the thing just works, as opposed to the person who purchases a Toto specifically because of its vaunted flush. That said, there is no denying that the reviews of those people who bought the 1G are indeed positive.
In contrast, the 1.28gpf version also gets stellar reviews, and those reviews are likely from a broader cross-section of people who purchased it for a wider variety of reasons and have a wider variety of demands. On a big merchant site, the Drake II CST454CEFG is routinely their number-one selling toilet of any brand, and it gets great reviews. It is definitely tried-and-true. And it has a simple flapper-based flush system, whereas the 1G has a more-precise but more-complex flushing device.