Compared to the EW Miley, the Butterfly is INCREDIBLY larger in the seat area, especially in the backrest length which is pretty much about 10 cm taller. So, yes, the Butterfly will be MUCH better for a taller toddler. However, bear in mind we're talking about ultra-compact strollers and that still means a smaller, narrower seat, as the main priority with these is to be super small, the most compact possible. You should be able to fit a larger toddler in the Butterfly, but don't expect him to have openty of space around himself. But that would also be so, I mean even worse, with the Miley 2.
About the exact length, I have not yet have the change to measure the whole, but I can make an educated guess of about 93-95 cm.