Yes this is an instashove. 8-handed, blinds 1200/2400 ante 200, one orbit = 1200 + 2400 + (8)200 = 5200, so your M is about 7.5. Add to that his 7500 raise, there is way too much money in the pot to do anything but shove when there are only 2 hands that give you worse than a coinflip. shove'n'pray!
