I've used the a Yashica SLR film camera before getting a 500D then after 3 years, went for a 6D. I won't go back to APS-C again after that. The shots I get from an FF and an APS-C is too different. Aside from that, high ISO capability for an FF is too amazing compared to APS-C. For events, an FF is really a joy to have.
You are comparing a current camera with 3+ year old technology. The ISO capability has no connection to full frame or APS-C, it's a function of sensor age. The 70D would have given you as big a bump in ISO capability at nearly half the price and allow you to continue using your APS-C lenses. I could compare a 5D classic with a 7D and conclude that APs-C is superior in many ways.