Avoid crossfire because of latency. You should be able to go all the way up to a radeon 7950 without a bottleneck because that's a good cpu. You could probably go with a 7970 if you were to overclock it.
I did have a 7970 paired with it without overclock and I upgraded to 8350 and it felt like I unleashed the card to its potential...I personally don't feel like the 1055t is a good cpu anymore its 2 generations behind just doesn't feel right pairing it with a 7000 series card again. What is latency and why would it micro stutter that is annoying btw...7950 sounds better in terms of price than 7970 and then again another 6870 sounds even better. Are two crossfired 6870 not do well or is it because of the cpu?
Two 6870's would do perfectly fine, and be the best bang for the buck, because you already have the first 6870. Will they be the fastest? No, but are you going to get the performance possible from a 7970, or even a 7950 with your 1055t, probably not.
Micro-stuttering is an unfortunate by-product of multi-GPU configurations. The actual seriousness of the issue is very subjective. Both the AMD and NVidia platforms experience it, but my understanding is NVidia's SLI doesn't exhibit it as noticeably. Either way, I doubt there would be as many multi-GPU configurations if the solution was totally intolerable.
As far as bottlenecking - there will always be a bottleneck. Whether it's the CPU or GPU, or something else, is up to the parts you choose, and the application.
Latency is the amount of milliseconds it takes the GPU to render each frame. You can have a high FPS measurement, but have latency spikes in crossfire which pretty much ruins the experience, for me anyway. It also depends what kind of monitor you have. If you are using just a basic 60hz monitor, then crossfire might be a good idea, but if you have a 120hz monitor with a fast response time you should definitely avoid crossfire completely because you will notice the micro-stutter a lot more.
Thanks for all your input guys great information, All I want is for her machine to sort of keep up with mine with as less $$ I have to put into it because my pc has been such a huge $$ magnet since I put it together and I still haven't yet bought an SSD. So two 6870 will have a huge effect on performance based on which it does now with higher in game settings on modern games. We play together and she moans over how much better my machine looks than hers so I wanna give her a better in game graphical experience as possible without buying a whole new system