the main place that you will notice the extra stiffness is in the bottom bracket area. so when climbing or pedaling hard the synapse will not transfer as much power to the pedals. i just switched from a salsa casseroll to a caad 8 and I was surprised that i find it more aggressive but not less comfortable. fwiw i am using 25mm tires, a carbon seatpost and a selle italia pro link saddle. if you like a little drop from saddle to bars then you will like the caad 9. if you need an upright position ie bars even with saddle then synapse