Man, Phoenix slab is no joke with that heat. I've done both and honestly tack strip works fine if the concrete is flat and you use the right adhesive for the strips, the kind that holds up in high temps. Glue down is more solid but pulling it up later is a nightmare and the glue can soften when it gets hot. Just make sure you test for moisture first, slabs out there can sweat and that'll mess up either method.