Onus :
A low profile HD5750 would be outSTANDing; would allow a competent mini-ITX gamer with a 250W-300W power ceiling.
I'm not so sure about that. The 5570 is the 3rd most low power consuming GPU in the 5xxx series after the 5450 and 5550. The 5670 power requirements are significantly above the 5570. Even more compared to the 5750.
Power wise, low profile cards don't really have a significant decrease over the regular ones. I agree with jyjjy on this issue. A low profile GPU's main purpose is to fit in to slim cases. That's why only relatively low powered and "weak muscled" GPUs are made low profiled. A 5670 already surprised me, since it would be quite difficult to limit the heat with such small PCB. Guess that's why MSI put the twin frozr as the cooling system.
5750 with a 300W PSU? I wouldn't trust my $150 graphic card with such low power PSU.
This is what AMD say about the card:
"450 Watt or greater power supply with one 75W 6-pin PCI Express® power connectors recommended (600 Watt and two 6-pin connectors for ATI CrossFireX™ technology in dual mode)"
Maybe you're confused between the low profile and low power consumption. If only both advantages can be acquired from the 5750. But unfortunately, the only way to have a lower power consumption card is to make the green series as in the Biostar lineup. With a passive cooling that huge, that would be like the complete opposite of this thread's topic.