You appear to be using an OC'ed CPU right? I recommend changing to a 600W at least in order to pair nicely with the R9 280X, it gives you some more extra headroom anyway.

Seasonic S12 II 620W, around RM299.

The V700 is a very good PSU, OEM'ed by Seasonic. Go with it without a doubt.

Definitely enough for you.

GTX 560 Ti is a ~ 150 - 170W rated card, so 2 pieces should be anywhere between 300 - 340W max TDP. Your 750W should be sufficient for your new intended setup.

The 520W is sufficient. However, I would suggest you to top up just a bit more and go with the 620W instead. Saves you the trouble in case you plan to upgrade to a more powerful GPU in future.

The VS650 is actually a pretty good PSU, though it does come with lower tier capacitors (from the review of the 450W model), however the product is well warranted so I do not think it is much of an issue anyway. As for single or multiple rail, there has not been conclusive evidence that one is better than the other, so any would do. I am not sure what series is the Antec model you've mentioned, but the EarthWatts Platinum model is quite ok too. Alternatively, do also consider the FSP Raider which is around the same price range.

I recommend at least 600W for your build. Some suggestions.

Seasonic S12 II 620W - RM299
FSP Raider 650W - RM259

Super Flower is fine. But for this HX series, I understand that they appear to use a slightly inferior main hold up capacitor, so it may raise some questions on long term reliability. But then again, IINM they are warranted up to 5 years right? I do not foresee this to be a main issue, besides this PSU is also priced very attractively and offers excellent for feature for its price range.

The PSU still under warranty? Else can consider this: Seasonic S12 II 620W PSU, RM299.