Uhhhh, its a very dated quad core , the top
Spec i7 in the 13 has a much higher clock speed. It'll be faster if not at least as fast
I think the experience will be similar, in my opinion. I mean, the 2014 really isn't THAT old. I mean that by probably not drop dead noticeable in day-to-day stuff. In terms of computing power, the two processors (4870HQ and 6567U), I think are a wash (We'll be able to see more details once scores start hitting geekbench, but I put my money on similar performance). If OP is looking to get out from under the 2014, I'm fairly certain the used market will never be more prosperous for folks scared of transitioning to TB3/USBc.
Here are some highlights to help weigh the options for OP:
The 2014 2.5GHz machine has 4 cores. More cores is WAY better for rendering/encoding.
The 2016 3.3GHz machine has two cores, but features higher clock
TURBO:
The 2014 machine beats the 2016 *slightly* in turbo, not by much. 2.5GHz can turbo up to 3.7GHz. The 3.3GHz can turbo up to 3.6GHz
CACHE:
The older processor has more L2/3 cache. | 2014- 256k x4, 6 MB | 2016-256k x2, 4 MB
RAM:
The new machine has faster memory. 1600MHz VS 2133MHz
POWER:
The 2016 is more energy efficient
DISPLAY:
The 2016 has slightly better retina display. You should notice more vibrant colors.
SSD:
Apple boasted in 2015 that the new generation SSD was 2.5 times faster than the 2014 models. The 2016, even faster...I can't recall the numbers off the top of my head...but if you're doing video work off the built in drive, you would see some faster performance with the new machine.
PORTS:
Every port the 2014 featured can be achieved with the 2016, if you don't mind shelling out some extra cash for needed adapters.
VIDEO:
NVIDIA 750m 2GB (2014) vs integrated Intel Iris 550 1.5GB. This area, I'm calling it a wash, in my opinion. Even in 2014, that Nvidia GPU was getting old. It debuted with the 2013 model. Some folks might be able to show specific benchmarks.
All in all, the 2014 was a solid machine. I personally have the maxed out 15" model. I personally don't see a need to upgrade at this time, it wasn't in my cards anyway as it hasn't deprecated to me yet. As you can see above, the specs don't speak to this being about speed differences. Intel/Apple are more interested in performance per watt. The 2016 isn't about huge performance gains, it's about energy consumption (and touch bar). OP, you've never seen a better time on the re-sale market. You can still command a great resale price as some folks are pretty passionate about getting their hands on 2014/2015 models (the two were very very similar). IF that computer is in good shape and you've got the money, go for it. I personally can't justify the price the latest model commands right now. Maybe in another year or two.