Pulse out while reading pulse in

We are in the early stages of planning a token dispenser with multiple hoppers. We would like to send the pulses out to the hoppers while at the same time reading the pulses in from the sensors to verify the token drop and make sure we dont over or under dispense. Question is, can we pulse out to 8 hoppers and read back from them using just the arduino or will we have to use another IC as well? Will we have to run the pulses serially? (pulse out hopper 1, read hopper 1, pulse out hopper 2, read hopper 2) which seems really slow

would using something like this work http://www.arduino.cc/en/Tutorial/ShiftIn ?

sorry for the complete novice questions.

You can likely sense a coin drop many times a millisecond using 1 pin per hopper or less depending on how you put things together. First big question is how your mechanical setup works.

Polling, doing things sequentially, can actually be a very quick and efficient way of performing a task. However you need to know what you want to do before deciding how to do it. Always keep things as simple as possible, only add complexity if it is really necessary.

If one of your problems is lack of I/O then look for the simplest way to get the I/O.

You can experiment very quickly on the Arduino to look at performing tasks sequentially or asynchronously. Try getting one hopper working exactly the way you want it then decide the best way to extend that to multiple units. A single arduino is almost certain to be able to control your eight hoppers, but your specification is quite vague at the moment.