Greeting fellow flyer: I used to be a Key-Board Warrior like you until I took a Prt Scr key to the knee. Subsequently moved on to a flight-stick and then HOTAS so I am accordingly qualified enough to investigate your 'complaint' for the purposes of ascertaining whether it's a bug or by design.
Have you for a moment considered that the behaviour you are experiencing/complaining about, ie
is by design? And no, please DO NOT compare the SU-27PFM with the SU-25T AFM and the Mig-29 SFM. Those Flight Models have absolutely bugger-all in common with the PFM of the SU-27.
Be that as it may, I had a look and discovered that the very same behaviour is experienced with the HOTAS as well as the keyboard, ie no difference whatsoever. In both the HOTAS and keyboard the pitch comes forward 50% as per your description when the stick is pulled back max aft. Now this conclusion leads me to believe that the IFCS is maybe to blame and that this is indeed intended behaviour, the flight computer's way of keeping you, the keyboard warrior and me, the HOTAS pilot, alive.
That said, I am obviously not 100% certain that this is indeed the case and will investigate further and let you know in due course.
You can accordingly rest assured that at present and as it pertains to the SU-27PFM, that there is absolutely no difference in input depending on what peripheral you use for flying: What happens to you and your keyboard is exactly the same as what happens to me and my HOTAS so no, you are not being ignored. Your keyboard is safe and accorded the same measure of fidelity as my HOTAS: May the most nimble of finger reign supreme :joystick: