I think everyone telling you not to mine either has no understanding of how mining works or they are just trolling.
I asked the same questions, ran the numbers, then bought some cheap 5850s... they have more than paid for themselves by this point and also got me a few more GPUs.
Everyone saying "mining is unprofitable" are probably mining right now and don't want you to take all their coins as if they will be able to prevent all new miners from entering the market.
I think you're right.
Before i decided to setup a mining rig, I read a lot about mining and most of the times someone say "it's not profitable". I've asked myself the same question.
I've decided to give it a try with some money that I can afford to "loose" in the worst case scenario. At least I'll never look back and say "What if I..."
I've invested 800 in a mining rig, been mining since monday, and finally for the 24h stable at 640Kh/s. I'm not rich, yet. But I've "earned" the equivalent of 20 in 24h.
For the moment I don't change pool, just giving a run.
Next week going to try multipool like hashcows to see the diference.
At the same time if you want to be even more profitable you can always trade your alt-coins for BTC and BTC for alt-coins.
To resume, I think it's still profitable and going to stay like that for a while.
that's my oppinion.