From what I gather tiled import gives you better performance because of hiding the tiles that are far from the player. If you wan’t them all visible at the same time then there should be much of a difference. But mentioning it’s a top down strategy style, why would you want all the tiles visible at the same time while you only have a small part of it on screen. If you are planning to go far above so when you look down you’d have whole the terrain in view, then I doubt you’d be able to see anything going on on the ground from such a high altitude.
BTW, There has been no note regarding this yet. 4.8 preview came out but still nothing about it. It was supposed to be a 4.8 feature to be able to render really large landscapes with good performance but it’s not in the preview and we don’t know if it will even be there in 4.8 final.