Not using a 700...but for general workflow I calibrate all of our machines in the morning, and its not uncommon to again have to calibrate later in the day to match something printed previously. Sometimes I have found it to help to run a little on the machine every morning before calibrating...not a whole lot, just maybe 10-20 prints. But also depending on your climate...I find that the color on these machines are affected by several different variables...temperature, humidity, electricity, developer life, and stock. So obviously if you proof at 8am when your shop is maybe cooler, and then you run the job at 11am when all the machines are running and its warmer...it will look different. We are using Fiery front ends and a Creo.
What you might find useful also is only using one densitometer (if you have multiple machines that you are trying to keep similar)...we do this on our 2045 and 2060 as they both have Fierys, so we only hook up the densitometer to one of them and use it for both.
Unfortunately the reality of these machines (by Xerox or anybody else) is that they aren't perfect for color always. The color is usually sellable, and you should be able to reproduce the same job over and over again with only a small degree of variance, but an exact match is just not reasonable. I would make sure to communicate with your customers that same expectation so that they know what they are paying for too with the lower cost of printing digitally versus offset. We sell our color as "similar" and use proofs and samples to manage color for critical applications and we are more successful that way than if we tell the customer that we will dead match everything.