I have seen the 7D getting bashed for bad high-ISO performance here, but I also realize that the standards on this forum is VERY high. Since I am not a professional, and probably never going to sell any of these pictures, my view of what is acceptable is somewhat lower.
To be fair, some of the standards on this forum aren't that high. Don't confuse who has spent the most or posts most frequently or whatever with ability.
That said, I do not want to invest a large sum of money into a camera that has bad IQ over ISO 1000, as I already own one of those...
I shoot stills with my 7D at 1600 comfortably and 3200 at a push. The key is in shooting RAW and being subtle with the sharpening and noise reduction. I find applying any NR first works best, then applying as little sharpening as possible, LUMA NR for lower ISO images where required, slight luma and heavier CHROMA NR for higher ISO.
The 7D is mostly maligned by folk who never bothered to set up the AF or cannot work RAW properly. One or two of the dissenters might have got a duff cam, but in my experience for the most part folk just bought a camera that was designed for personal set up, and never bothered setting it up.
The kind of folk, who in the first part of my answer, think that buying a more sophisticated camera makes you a better photographer.
If you compare photos of resolution charts with those from a 5D3 or 1DX then the 7D isn't as good. Handy for those who shoot resolution charts and can afford a 5D3 or 1DX. Which many folks can't.
Within your budget, with your lenses and for your application the 7D is the camera to go for. Just be prepared to crack the manual. It'll really sing if you add a fast aperture USM lens (something like an 85mm f1.8 or 100mm f2.0)
So, the question is: How bad is the 7D on high ISO (1000-6400)? Really?
If you are confident using RAW you'll get great images at 1600, good images at 3200, and 6400 is probably more akin to what your current camera is giving you.
Bear in mind that super-high ISO is a relatively recent trend. I remember the noise from Fuji 1600 print film, to the point where I'd usually restrict myself to 800 or lower. So it's changed days.
The only arguement I can think of to get you to hold off from buying a 7D just now is that there is a new model pending, you might be in line for a bargain on the 7D if you can wait a while.
In the meantime, get to grips with RAW, as it makes the absolute best of the 7Ds images.