^^^^^^ This. I rode an indoor, then got the westmark this year, and I love it, to me the westmark feels a tad softer but not much, but the indoor has flat kick where as the arbor boards are rocker so there gunna be a little different, but get the westmark or blacklist you won't be dissapointed.
Arbor doesn't have any flat boards so none of them are going to feel very similar underfoot, but as far as filling the same type of role, the Westmark/Blacklist would be similar in that they are mid-flexing park boards that do well outside the park for all-mountain freestyle type scenarios.
If you like Flatkick, try K2 Jib Rocker (Parkstar or Fastplant) or Signal Park Flat. I just took my Park flat out this weekend for the first time and it's pretty fun. Just waiting for it to soften up.