I shoot 6x45 which is almost a 6mm TCU (different neck)with bullet weights topping out around 107 grains.
I commonly shoot 70-75 grain bullets around 3000ft/sec out of a 20" barrel.
It seems to hit coyotes a lot harder than the parent case 223 as well it shoots flatter than the 223 with the same bullet weight.
I've thought about a 7mm version but the case capacity is the limiting factor for me as the speed drops off too much for my liking with ther larger 7mm bullets. A better choice for me was the 7mm-08 loaded light.