It's not an issue specific to FX, but to all overly complicated platforms. Steyr, Anschutz and FWB can suffer from the same issue resulting in an increase or decrease in fps, as well as frame movement. The fps change is managed with a chronograph and hammer spring adjuster if caught before the match. As for frame warpage/movement a very sturdy bridge is used to help with frame flex. So those fancy risers on the brands mentioned are more for platform stability than getting the scope up for proper eye relief.
P.S. You're not likely going to hear much from FX users about temp shifts as from what I can tell most are shot from under a covered bench and when pesting a shift won't be as noticeable or simply chalked up to wind.
A good test is to start by shooting 10 single bulls at three different ranges(10yd, 30yd, 55yd) in the morning with the gun at a "stable" temperature. Then put the gun in the sun and let it get hot. Set it in the sun for an hour. Shoot the same course of fire, let the gun cool and do it a third time. This will also be a good test of how much your scopes poa, and ranging might change with temperature as well. Oh, chronograph use is mandatory in this experiment as well.
Of course if all you want to do is shoot and have fun then ignore this. But if you get frustrated missing shots that shouldn't have missed you may want to look into it.