Yes live rock, is basically limestone (when using them in a freshwater environment), and yes texas holey is basically limestone also. There is nothing wrong with limestone if you are shooting for PH ~7.6 or whatever the magic number is. Just use what you like best, then just know that with stones that are like limestone they will leach so your water parameters will change over time. Unlike if you use something like Lace Rock (volcanic) that is basically inert and you set water ph and such by adding Seachem products with the water.