SR5 is a step down from TRD, but maybe it'll ride better, or take more narrow (cheaper?) tires. Not sure on what is different in options between 2014 TRD and 2016 SR5.
2WD ought to eek out a pinch more mpg, have more towing capacity. But it doesn't appear that you are racking up the miles either. I think you are better off keeping. The new truck will depreciate to a level below what yours is after a couple of years (2WD and SR5, it's a lesser model). Unless if you need a more compliant ride or better mpg or some option that the '16 has that your '14 doesn't, I think you wind up with less after this trade.