Your best bet is to save up to get the newer one. I personally am not a fan of the new one but that is because of the aesthetics of it and the price. As to what Ty and Alton mentioned, the new system has a lot more items to monitor like power consumption and has a built in wifi setup. Other than the look and feel, its pretty much the same with supposedly a stronger brain to process the new modules like the Trident. As far as I know, everything works with the classic except for the new Trident and possibly the new COR pumps as well.

In the long run, its best to just upgrade the system to the new one. I have 2 classics and I will eventually upgrade my DT to the new system. I just need to raise some funds and sell corals to get there.