Need opinion on interface for new setup

Im getting things ready for a new setup starting from scratch. So I bought new focusrite scarlett 18i20 for a good price. I then came across a great deal on a new Liquid saffire 56. I know there will be no problem hooking these 2 up with a standalone and adat connection. I want to be able to record 16 tracks at one time. I have a new macbook pro retina 2013 with 2 usb3 ports and 2 thunderbolt ports. I like the idea of using the thunderbolt port with the adapter for the liquid 56 and freeing up my usb ports for ilok and 2tb external hard drive. My question is, I know I'm keeping the liquid 56 and since i haven't opened up the 18i20. Do i send it back and buy another Liquid 56 so i have 2 more liquid pre's for recording acoustic drums (which is my main purpose for all of this) Or is the pre's in the 18i20 just as good as the pre's in the liquid 56? Keep what i got and save the money for future plugins? I don't see anyone using these two units together but the routing options are huge. I will be buying PT 11 within the next week. Thanks for any opinions.