Well I have an FNX-45. Not the tactical version, but I can answer you questions.
Reliability: I have over 500 rounds through mine (haven't had it very long) with no malfunctions. I don't know for sure that it will always be 100%, but all indications point to yes.
Durability: I haven't abused this gun, but it seems to be very durable. Note that you CAN NOT detail strip the gun. It was made so that it is NOT user serviceable beyond a simple field strip. (unless I don't know about it)
Accuracy: It is more accurate than I am for sure. Accuracy is not even worth talking about when humans are a variable.
Ergos: It is a really big gun. I mean really big. Huge. 15 rounds of .45 acp in a magazine. That being said, it is comfortable to hold and a verryyy soft shooter. The DA trigger pull is extremely heavy. My Sig 226 trigger is 12 lbs and the FNX trigger is even heavier. It is very smooth. The SA trigger is pretty light. The break is analogous to a rubber band snapping.
WEIGHT: The gun weighs 34 oz unloaded. Each loaded magazine weighs about 1 pound. 34+16= 50 oz loaded. If you'd like to have two extra magazines like me, then you're carrying a total of 50+16+16=
82 OUNCES. That is
5.125 pounds. Carrying that is not fun. Not fun at all. Even if you don't carry any extra magazines, you've got a 3.125 lb smoke wagon on your side.
Overall Experience: The gun is a blast to shoot (no pun intended). It is too freaking heavy. Wayyy too freaking heavy. Every bit of the gun they could make out of polymer is made of polymer. The safety/decocker is polymer. It feels like a lot cheaper of a gun than the price you will pay for one, IMO. This is very apparent when comparing to the predecessor, the FNP, which used to retail for around $400. Neither the manufacturing process, quality, or materials changed with the FNX, but boy the price sure did. And getting the magazines.. It is more likely to find a unicorn in the wild.
I like the gun. It's uses are limited (for me) to either a range gun, home defense, or a truck gun. It is not useful to me in any situation where it needs to be carried.
Rating: 7.25/10
My .02