If you are missing more THAN a few shots due to noise or motion blur, then you need to jack the ISO up. And learn to properly expose scenes. "Noise" ought not to be a factor until ISO 1,600 at the absolute lowest ISO level, and probably at ISO 3,200 your camera will be somewhat noise-prone. Many new digital shooters fret and worry about noise. Noise that is so,so,so low I often laugh at the suggestion that an image has "noise" when it is brought up on some web board. I'm not laughing at you, per se, but merely at the way today's young people find even minor noise levels horrifically objectionable, in an almost comical manner, like, "Waiter! Waiter! There's BEEF in my HAMBURGER!"
If you have a 50/1.4 and a 17-55 2.8 Canon and you have issues with noise and with blurred images, it's not better equipment that you need. It is knowledge. And skill. And technical knowledge. And I say that as somebody who started in photography when ISO 400 was considered "fast" film, and available ONLY,and I mean ONLY, in black and white. I was in junior high school when ASA 400 color negative film was invented, and ASA 160 color slide film was considered "very fast". Arguments raged over the superiority of Kodachrome 25 versus Kodachrome 64. Seriously! And both those early color films had image character that looked about like ISO 1,600 does today from a cheap, entry-level d-slr. And yet, millions of people made compelling images, blur-free, with crummy zoom lenses that were not as fast as your f/2.8 model.I learned to shoot color on Kodachrome 64. ASA 64. SIxty-four!
It's fine to admit you want a Canon 7D. I looked art your other thread, asking for comments on how you might improve. I think the one thing you could do is probably to start shooting at ONE of the higher ISO settings, maybe for 10 days at a time, and actually,literally "SEE" how your images change when you are free of slow shutter speeds. I have a feeling that you are tending to shoot, as I call it, "on the margin", probably without realizing it....speeds just a litle too slow....exposures just a little too far to the left on the histogram...maybe you are doing the cardinal sin: evaluating your exposures by LOOKING at the LCD IMAGE, and not the histogram...