The regular arduino has a sampling rate of 15 khz do you think with hand motion (rpm max) that a regular Arduino UNO could keep up with these or do I need to use something like a DUE?
15kHz? No, that can't be right, digitalRead() takes about 5us or so, so reading two pins takes 10us - 100kHz rate.
analogRead is limited to about 10kHz, perhaps that's what you were thinking of?
With direct port reading you can read up to 8 pins simultaneously in 125ns or so... The response time of the interrupt
handler will be the limiting factor, and again that is a few us.
I think with 4 encoders you'll need to look at using pin-change interrupts to drive the encoder reading, and
direct port reading. There are probably examples of both on here if you search for them.