Okay so not sure if FSX:SE is the same are P3D when it comes to controller add-ons like Saitek, but I can confirm the multi panel, switch panel, and pro panel all work with the SVJ. I use SPAD.NEXT to interface the Saitek panels and I can program all the lights and AP functions to work properly. I can assign the levers on the throttle quadrants (I have two) directly through spad to control flaps, throttle, and speed brake.
The only issue I have with the pilatus I have found so far, is editing the flight plans. I seem to loose the function of my keyboard somehow. I will report this bug to Iris themselves. Once they iron out the MFD/PFD controls to be a little more smooth, I think the product is a hit.
Overall this is a very nice product. There are updates that Iris plan to accomplish in the near future. So the IAS climb modes etc. might get looked at. As of now, the textures are great inside and out. Looks just like the PC24s I have seen in images and countless YouTube videos. Not sure where all the hate is coming from. It is a very simple and intuitive aircraft in the RW, so I think Iris captured this mindset properly.
Last remark I will make. The performance hit on the system is nominal. Since Carenado was brought up here, i'll say, the PC24 has less impact on performance than Carenados with the Pro-line avionics installed.