IC60 is $1700, 2lb/day, = .4FC / hour = 10FC at 100% for 24/7, or 7.3FC at 70% output for 24/7.
IC40 is $1249, 1.4lb/day, = .3FC / hour = 7.3FC at 100% for 24/7
Rated life is 10,000hrs.
10,000 * .4FC = 4000FC Total production
10,000 * .3FC = 3000FC Total Production
$1700 / 4000 = $.42 / FC
$1250 / 3000 = $.42 / FC
They work out to about the same $ / FC. (Sneaky smart, those pentair pricing guys...)
Texas demand can be 3-6FC daily, with sun and swimmers in the summer. (certainly depends on your CYA level).
4000FC / 3 = 1333 Days
3000FC / 3 = 1000 Days
*NOTE* Your demand will vary with the seasons, I'm just using average math for illustration.
As Mark said, likely you not use a cover in the summer, you pool will get very hot, and likely higher demand without the cover.
I recommend the larger cell, because when I have a lot of people over on a sunny day, I can turn my 60K cell up, and it can handle ANY FC demand I can throw at it, I don't need to supplement with Chlorine. And, I get another year of life out of the cell before I have to shell out money.
Is your pool in full sun or is it partially shaded...that makes a difference too. Both cells will work.
Your value equation may be different than mine, I hope this helps your decision.