FMJ are 11+/- grains per inch. They are heavy, but if you are pulling weight you will get awesome energy and complete pass-throughs. I use them as my main hunting arrow. They are durable and the HIT insert is kind of nice too. The carbon express are good arrows too. Lighter and will have a good trajectory. It really depends what you are after.
I have used both and they re both great arrows. I go hunting in Colorado and shoot more than 30 yards, so for that reason decided on the Carbon Express arrows due to weight.....
I've always used CX and continue to do so (if it ain't broke...) my sister and brother in law both use the FMJ's and they love them.