I have the 28 f1.8, 50 f1.4, 100 macro IS USM, 24-105 f4, and my DSLR is the t3.
I think you have two questions here:
1. Will a full-frame camera be beneficial to me with my current lenses? In my opinion, absolutely. I upgraded from a 40D to a 5Dc about a year ago with a very similar lens lineup (28/1.8, 50/1.4, 85/1.8 ) and I've barely touched the 40D since. The 5Dc image quality is noticeably better than the 40D, and my lenses (similar to yours) shine on the full frame format. Yes, this is true even for the 28/1.8 with its supposedly soft corners - it's better on full frame. Maybe you'll be less happy for your landscape work, but for my indoor family shots, I love 28/1.8 with 5Dc - probably my most used combination.
2. Is a 5Dc the right full frame camera to get right now, given the current prices? In my opinion, not really, unless you simply can't afford a 5D2. When I bought the 5Dc, the price difference was huge ($800-ish vs. $2300-ish) so the choice was easier. Now.... 5Dc has come down a bit ($600-ish used) but the 5D2 has come down a LOT ($1300-ish used, can get as low as $1500 brand new). If I was a buyer right now, I think I'd pinch my pennies and go for the 5D2. This is nothing against the 5Dc - if it's all you can afford I still think you should do it - it's just that the 5D2 offers a lot of upgrades for not that much more money.
Hope this helps.