First and foremost, dont listen to any SH idea of using LED to brighten up the room. For some fancy corner visual effect or narrow corridor fine!

LED output and brightness is the worst in terms of per dollar! Also the reliability is questionable as too many china mali!

Even the GE or OSRAM can be fake also what with LED without branding.

Since you rewiring and plaster ceiling to be done, I suggest you to work out with your cont to have separate switches perhaps 1 switch for 2 downlight. When chosing down light go for 6 or 8in size. Anything smaller is useless and cant accomodate higher watts bulb.

You can chose the round vertical or Square horizontal. With the square horizontal, you can opt to 2 bulb per point. The upgrade cost is very minimal. Your wall color and furnishing can dictate the brightness so if you have twin bulb system, you can remove one when its too bright.

My living room is about 28ftx16ft. I have only 8 single down light with 18w each. The one near the wall, I have it on warm yellowish for ambience. the rest just warm white. I also have a track halogen light near another wall for ambience and mood setting each one is 30w. Because of my living/dining, I have 2 lamp shade hanging down at 18w each.

When I want it bright, I just own 4 down light and thats it. Switching on all will make it brighter than day time. My friend did the same but he was on twin bulb, ended up he have to remove one bulb each to prevent night blindness glare!