I've used the Hornady when it was still Stoney Point and I have the Sinclair steel inserts which also fit into the Hornady gauge body. They both work for my needs as long as you realize they are Comparators, not headspace gauges.
I did pickup a 30/06 and 308 Win. RCBS Precision Mic at an Estate sale for less than half of their value. They are calibrated with a Headspace gauge to be @ SAAMI Minimum @ the zero mark. They work well, but at retail cost, they're expensive for one caliber. For me , the Hornady set was better due to all of the different Rifle cartridges I reload.