I use FSX and X-Plane. I already have a yoke/throttle/rudder pedals. I agree, they vastly improve the experience more than anything else.
I currently use a TrackIR with two monitors, but truth be told it's a bit janky and I find it very difficult to visually tell angles (for example: what's the angle of my plane to the runway? I could use the heading indicator for that purpose but I don't want to develop bad habits for real-life flights).
The hands thing would let me flip switches in-cockpit, which is nice. No more mouse!
Not sure what type of flight sim you are into, but using a proper yoke, throttle, and rudder pedals makes the experience much more immersive.