Fitzroy1965,
While the durability of the G13S is 2.0 compared to 2.5 for the cally, that translates to around 20 shots based on number of shots posted elsewhere in the forums. They are still a good lower priced ball compared to the Callys. I do acknowledge in ball choice you do get what you are willing to pay for. The Nike LVL 61's I use sometimes are much better that the Callys, but twice the cost, for example.
I (and others ) have disagreed with Solarflares about the G25 driver and woods before. Some of us used them and they were very good for us at that time, and he feels they were junk. My recommendations are based upon my working within a budget and using those clubs for a while..
Some of it comes down to personal preferences. When I bought them it was cheaper to buy the set and later sell the hybrid and 3w back than to just buy the irons and driver. Since I wanted a better driver, temporarily until I could buy the SLDR @ LVL 79 my way worked for me.
Best thing is to rent first if possible, and see what works for you.
phred952.