Why use Kickstart 3.1 rom if you plan on playing adf files from the gotek ? You'll have many incompatibilities with games that don't work. Most ECS/OCS games require 1.2/1.3/2.04 Kickstart roms. You'll have to resort to ReloKick or similar programs to avoid incompatibilities.
3.1 on the other hand, is a great option if you're planning on using your 600 a bit more. That means installing a humble accelerator (ACA,Furia or Vampire), some extra ram and a CF/SD card for a hard disk. Then you can get really going by installing all the games you want in WHDLoad version!
Currently my Amiga 600 is more or less like that : Kickstart 3.1 , Furia 020 Accelerator, A604n Memory expansion, SD2IDE adapter, KA47 IDE Riser and an 8GB Sandisk Ultra SD Card.