Multiple deployment servers in 9.1

I  have a question about if anyone has set up multiple deployment servers in 9.1.

I have a customer that tried to split the dev/test environment and production environment into two locations .  They only had one deployment server (in production location) and when they tried to do a full build in Dev/Test it took 72 hours. They finally moved all servers into one location and then the full build took 4 hours.

They are going to be upgrading to 9.1 (currently at 8.12) and they still want the dev/test in one location and Production at another location.  I suggested that they have two deployment servers one for Dev/Test and the other for PD.