Sure, there is effort involved, but from my point of view it's a small one (a couple of man months on a project with 50+ coders). I'm going to have to make adjustments between the platforms because the hardware is different. Even on a DirectX PC, you can often have a lot of differences between the rendering scene for Nvidia, AMD and Integrated Intel gpus.
Don't know exactly what issues Everspace had with the UE4, but you want to have a fun night go out with some Epic licensees and get them to tell you war stories of issues they have had when they tried to do something which Epic hadn't done in their games. You're paying Epic for the "battle testing" and often they didn't fight those battles.
Part of the reason I left the games industry is that once you work at studio with an internal engine it is extremely frustrating to work on AAA games without the freedom to walk over to the engine programmer and get them to move the engine closer to what you need.
Don't know exactly what issues Everspace had with the UE4, but you want to have a fun night go out with some Epic licensees and get them to tell you war stories of issues they have had when they tried to do something which Epic hadn't done in their games. You're paying Epic for the "battle testing" and often they didn't fight those battles.
Part of the reason I left the games industry is that once you work at studio with an internal engine it is extremely frustrating to work on AAA games without the freedom to walk over to the engine programmer and get them to move the engine closer to what you need.