You'd notice a big difference between the 560s and the 560Ti's in SLI, or at least I would. Definitely worth it IMO, though both setups are a great value. If you go for 570s, I'd recommend dual-slot cards, or at least one dual-slot to run on top. You have the best cooler on the market on that thing but if you ram it up against the PCB on the next card, you're shooting yourself in the foot. That mobo is triple spaced for it's SLI slots, so I'd take advantage of that. If you do go for a triple slot card on bottom, you'll want to check first to see how much room there is between it and your PSU, so that you're not shooting yourself in the foot there.