I was in a pretty similar situation recently. After more firewood was thrown on the fire, I decided to start looking, and at that point I had already decided not to accept any counter-offer. Not only was I being shortchanged on salary (significantly), but also in benefits, perks, and working conditions. I'm really happy I found an awesome startup in SF that still after a month feels like an ideal workplace for me.

When I was looking, I was disconcerted when I found companies with no personal growth prospects or that flat out said they wouldn't pay what I was asking (fair) because they didn't want to pay two engineers with the same title too differently. I asked if they would offer bonuses to compensate or if they'd consider paying the other guy the same salary, because he seemed smart enough. No to both, and I felt that alone indicated that management there didn't value engineering talent.

I really hope this treatment of talented workers isn't too pervasive in the industry. Pay people what they're worth. Strive to offer the best working conditions, benefits, and perks. Take the values of your employees into consideration. It really doesn't seem like it's too much to ask for. And personally, I'm all for complete transparency within my company, even to the point of salary information. I think it would resolve more issues than it would cause.