@AstraSPx
Are you sure about your cruise speed and MMO?
I spent 13 years in the IAI 1125 ASTRA and it was a 0.78 cruiser with 0.835 MMO. Is the SPx different?
Also, regarding GLEX speeds...
A quiet flight deck to be sure but anything above 320 KIAS gets unbearably loud up front. Don't know why one would want to fly faster. You are only in this realm in the teens during descent anyway.