Seem to be coming to this party a little late.
Just to say, I had "gone off" C1 sometime back, that is until the Fuji X-E1 came out. Here I had little choice but to get back to C1. At the time and other than Fuji's rather lack lust 3rd party offering, C1 was about the only other option available when it came to processing Fuji's RAW files.
My timing was good, as this was when version 7 had just came out. All I can say is, I was "astounded" by the results I was getting off the X-E1. I was doing a lot of "remainable" light work with this little camera and was often shooting at ISO 3200. At the time ran some tests using Adobe's ACR and C1 and the results were telling. There was nothing scientific to my testing - just enlarging sections of images run through each process and checking out things like shadow detail and colour shift. To my eye and senses, C1 scored every time.
Back to using your Canon 5D MkII. Recently have just "recooked" a whole section of image archive using C1 7.1x.x - namely much of my architectural photography. At the time was using TS 17mm and 24mm lenses on the 5D MkII. Much of this work was shot in 2011 and 2012. Again, as I redo these images, I'm quite astounded by the results I'm getting from C1.
When first prepping and processing these image I was using Adobe's Camera RAW via Bridge (having long given up on Lightroom) and then using Photoshop to clean up and "tweak" the images. All in all, the results then were largely flat, lacked detail in the shadows that I shot for and lacked any sort of pop in the highlights. I couldn't pull the results as I had envisage them at the time the images were taken. As a result, was quite embarrassed with these results. Tried DPP and there, things weren't much better. In that period sort of shrugged off these results and largely put this down to my own "bad photography".
Long story short, after running these images through C1 7.x.x felt decidedly vindicated - this in that the "results" I was looking for were there all along. Seems like the technology I was using previously wasn't up to pulling and producing the results I was looking for. Now, with C1, I have those results and I'm now more than pleased with the outcome.
Also need to add here that I'm in the process of "reworking" images shot on a Canon EOS 1D MkII as well as some early conversion DNG files. All the results now seem a lot better than when I first worked with these files.
I think this eludes to Kevin Raber's point - that this transition from what I was using before (ACR and DPP) to using C1 7.x.x has been like getting a new camera - if not "literally", then in C1 making better sense of all the image data that's always there. As something of a "qualifier" here need to add this, like cooking, what works for me may not necessarily work for you or work quite in the same way. C1 is a bit like getting into a kitchen - you'll need to "brew" up your own recipes to get things working to your own liking. Wish you luck in this regard.
BUT, just to balance all my enthusiasm here, I'm having issues with 7.1.3 and have had to "downgrade" to 7.1.2. Not sure what the issues are yet. Might be the computer hardware I'm using. It may be something else. However, please don't let this deter you.
As for "upgrading" your computer hardware - get it done. You ought to be looking at minimum of 8 Gb of RAM, a multi-core CPU and a LCD monitor starting in the 22 inch range. How you get there is up to you.
Hope this helps - Rogan