I use omnigraffle every day. Recently tried to create penrose diagrams but discovered you can't create custom open-ended shapes; and modifying any of the few open ended shapes they have closes them. Guess I can't hope for any improvements any time soon.

OG is probably the main reason I'm still on a mac. Nothing else comes close. I hope they can rethink their plans and create a more sustainable & successful business. Their other apps are pretty good too. Easily the best software shop for mac.