They are awesome processors, but it's like putting an intel i7 in a computer with 1 gig of ram... there's just not enough to process as it is, so what's the point?
Throwing in dual digic 5's in a 1DX that's shooting 10fps at full frame raw, and does it FOREVER is totally different than a new t5i that can do what.. 5fps? My 20D from 8 years ago does 5fps and still processes it all pretty quickly...
The sensor is a great sensor, it's just when you put it in a rebel and limit everything it can do speed-wise, it changes things. They also don't throw in 1080/60p so they're limiting everything there, too.