nope. all the radeon 1x00 can do it.
How? If you multisample (as pointed out in another post above) in a higher dynamic range you can't then antialias it after the exposure pass. You may be able to turn multisampling on but it will only work if you are completely in the range you will be exposing to ... and if you are .. why are you using HDR?
Its a fairly simple reason it won't work ... how does it deal with a pixel that returns the following 2 multisamples ... 16,000,000 and 0 ... logically you'd choose down the middle at 8,000,000 (and yes i know im simplifying this) but at that value if you then expose into the range 0->1024 (yes everything will probably appear very bright) then that 8,000,000 value is still well out of range and the multi sampling is not providing you with decent results...