I don't see how it is a problem seeing that you have to be at 250 kts below 10,000' in most if not all airspaces in the world.
Not in the London TMA if they give you free speed....
Quite happily get 270kts in the CJ2+ - as said, you get to 8000ft, and then VMO drops to around 263kts IAS, and if you forget that (as previously mentioned), you do get a nice alarm in your earholes hehe - you only forget once or twice after that ;-)
Oh, CJ2+ MMO I think is M0.737, usually with a good ISA and FL450 Cruise, you can expect say M0.71...
F/o