CO2 resistant tubing will not harden and crack like the normal tubing will. You may also lose some CO2 through the normal tubing. I read one post on this site that claimed a 20% through normal air hose v.s. CO2 resistant. Not sure where you can purchase. I would try a LFS (not Petco or Petsmart).
I did some testing of silicone tubing, because theoretically that is the most leaky of all tubing types. I did not get any leakage. I had a 25 foot coil of the tubing, plugged at one end, the other end pressurized to up to 40 psi. No bubbles came out of the tubing, and no CO2 flow occurred - I had a normal bubble counter to measure the flow.
My conclusion was that even with the worst tubing, we don't lose any CO2 through the tube walls, so it is best to use the tubing that does what you want, without being concerned about CO2 loss. If you were to have a 250 foot run of tubing, it is possible that you would get a very slight loss of CO2, but not with our typical 10 foot or shorter run of tubing.