Multiple LED panels?

I am not sure you will get brighter but will definitely get more efficient. I did 42SMD soft white round to replace my 921 bulbs and the lumens were 1/10 the incandescent. That was not really an issue for us as we do all our reading on backlit ebook readers and tablets anyway, and we preferred it not being as bright as an operating room. I would definitely get the flat LED's and get them in bright white if you want brighter. Some people have indicated that good brand name bulbs are brighter than some of the cheap ones off eBay. Even with 2 you may still be less bright than the original bulb though.
I did a full write up of my experience doing the LED upgrade with detailed brightness testing.
https://rwbradley12.wordpress.com/2015/08/24/led-light-upgrade/