Light aircraft tend to produce quite strong fluctuations of vertical speed when operated in FLCH in descent. Climb is always okay, but beware in descent. I used to fly Citation XLS and we practically never used FLCH in descent due to this - it could be really uncomfortable. Rather use VS and watch out for your IAS. And if your plane is limited to 250 KIAS then rather give it some margin and fly max 240 KIAS - that will avoid headaches. If ATC requests 250 KIAS, just tell them that your unable and that your max speed is 240.
My current aircraft does not even have a FLCH-mode for descent. For climb there is a CLB-mode that is nothing else but FLCH, but can only be used to climb. For descent we have to use PATH or VS and it does work very well.