Actually, TCCD isnt very rare anymore. OCZ went back to TCCD, Patriot XBLKs have always been TCCD, G.Skill has a HUGE variety of binned TCCD. So its very common now and at an insane price! And running at 2T depends on the memory controller of the processor too. CAS1.5 is only faster on the DFI LP SLI-DR Experts. Its because with the rest of the motherboards, CAS1.5 doesnt exist, its non-existant. So it thinks its slower.
EDIT: Ballistix run very very hot. And there have been cases of them dying and needing an RMA. All Micron ICs tend to run very hot even at 2.8V. TCCD is a much better choice, but UCCC is also very very good. You will get better overclocks with 2x1GB but if you only want 1GB, then get 2x512. I highly recommend 2x1GB though.
EDIT: Ballistix run very very hot. And there have been cases of them dying and needing an RMA. All Micron ICs tend to run very hot even at 2.8V. TCCD is a much better choice, but UCCC is also very very good. You will get better overclocks with 2x1GB but if you only want 1GB, then get 2x512. I highly recommend 2x1GB though.