In all honesty, once you understand the FKG main mechanics from the Nutaku version, and transition to DMM it gets some time to get used to, however due to the prior experience its not so bad. There are many "comfort of life" adjustments in DMM version (extra 200 bag slots as additional storage, 6 Raid points, an actual use from every dupe you get and sell, plus of course bunch of new girls to gather and evolve/bloom).
There are also very hard stages, which bring some sense of accomplishment as its not so easy to clear. I would love to see them in Nutaku version as my team while not the most OP team ever, can pretty much clear any event without as much as a hitch.

Also there is a DMM thread on this board, where you can always ask the questions. I too was at loss when I started the DMM version, but thanks to the other players advice and info I managed to get used to the new mechanics relatively fast, and now I dont find them any more baffling as I had before.