Easier to handle is size based[1]. The smaller size generally means less weight than a bigger iPad of the same generation.
I am a bit worried about Apple's desire to remove the bezel since that will cause some problem and iBooks likes to flip a lot of pages if your thumb strays.
1) [edit] the iPad pro is just a no go because of its size, and the iPad 9.7 is too big for a lot of children and some adults. Remember, a lot of activities are hold it up with one hand for long periods of time while tapping with the other.
The handling issues has mostly to do with weight rather then size. If someday the iPad 9.7 has much less bezel, half as thick, and much lighter. Would that still be a problem?
I think that is where iPad is heading. Some argue Apple is obsess with thinness, personally I think both iPhone and especially the iPad has a long way to go before it is Too Thin.
Nope, the size is the big thing. Weight is a factor but the mini is a good size for holding. The 9.7 will always be more awkward than the mini. So, yes, a lighter 9.7 does not replace the mini. That argument is the same as saying a lighter 12" could replace the 9.7 which doesn't work because the 12 is painfully awkward to use.