Those aren't bad times. A tri bike will make you more efficient and therefore faster. The weight difference will knock some time off as well, but the most important element is the engine, you, for real time savings.

An entry level tri or even road bike will make your life easier out there when you can swing it, but you can probably still squeeze off some time with the bike you have now until then; more miles+more hills = more better.

Then there's always the cool factor of having a new bike, that's always good for a couple.:)

Nobody can tell you with any precision how much time you'll save--but we can guess. I think if you're going 19MPH on a hybrid in an Oly then it might make sense to look at a tri bike simply because improved aerodynamics and rolling resistance matter much more if you're trying to go faster than 19MPH than, say, 15MPH.

I see that your bike is specced with 700x35C tires. If you aren't currently using skinny (700x23C or narrower) tires and aerobars, I think it's a reasonable assumption that a switch to a tri bike with both of those things could net you 1 to 2 MPH (folks, chime in if I'm way off base here). At your speed that translates to roughly 4 to 7 minutes in an Oly. The entry level tri bikes you mentioned both provide great "free" speed compared to any hybrid simply because of superior positioning in the aerobars, narrower wheels/tires, and, to a lesser extent, lighter weight.

All this assumes also that you gain no additional fitness--if you keep training, those gains will also translate to additional time saved.