Did you use your Nikon often enough to get a feel for it?
The Canon's do things differently. For openers their lenses are removed the opposite direction. The control and menu layout is similar but not identical. Also in comparing the sensor performance those Canon's lag behind the Nikon you mentioned.
I'd suggest you not buy a new camera. But instead 'focus' on getting the most out of the one you have. Maybe add a prime lens like the low cost 35mm f/1.8. Learn to use the various modes. That camera will more or less match the current Canon's you are considering upgrading to. So why upgrade?
"Old in technology terms". It's about you, not the camera. The 3100 offers plenty of features. They started focusing more on video features, is that what you're after? If so, by all means upgrade. With that said, might as well go with Canon for Magic Lantern, I use that all the time personally.
I still shoot with a D90, which is almost a decade old. If you're upgrading in the hope that you'll take better pictures, then you'll be disappointed and have wasted your money. New technology doesn't take better photos.
I agree with bjornl in that you'll be far better served by buying a lens or two. The 35mm f1.8 is a good start, followed by an inexpensive telephoto, wide-angle or macro depending on what you shoot.