Anyone who is using radeon 7950 or R9 280X for mining scrypt based coins please let me know how much hash power you are getting.
2X 7950s getting +/- 1.35Mh/s.
Could push them a bit more (and have done so) if I wanted but prefer longer lifespan to higher hashrate. The max achieved per card is about 720Mh/s but not really sure they work efficiently at that high of speed. Performance/efficiency is just right at 650-680Mh/s. In my humble opinion and in my personal experience, maximum achievable hashrate isn't the only thing to consider in a card.
7950s are good cards, a few months ago they were arguably the best choice to consider for scrypt-mining. Now though, they've jumped up in cost and are becoming more and more difficult to find...the 280 or 280x would probably be a better choice currently....though I don't own one yet so this is speculation. From what I know of them, you basically get a newer/improved 7970 for just a little bit more cost (if any) over a 7950 (feel free to correct this claim if it's inaccurate) and around $100 less than a 7970.
So its best to get a R9 280X in the current situation?
Perhaps. Hell, I don't know...just what I would consider doing if buying another card today. Well...that is, if you can find one.
Don't listen to me though...as stated previously, I don't own an R9 card.
You asked for hashrate of 7950s so I offered my own experience...the rest is only personal opinion based on speculation. Honestly, what's best is to do your own research before making any purchasing decision and don't ever buy anything just because some numskull in a troll-flooded forum told you to.