Best setup for two location and multiple monitors.

I'm looking at options for a setup for two locations. Work and home. Mainly I'm trying to figure out limitations of various Mac models. Also the best option for keeping in sync.

Options 1: Macbook Pro 15". This seems like an ideal setup. As only one computer needs to be purchased and there are no sync issues as the computer just gets moved back and forth. However, I have concerns about its capabilities.
Will the current 15", 2.8Ghz i7, 16GB RAM, 1TB SSD and Radeon R9 M370X be capable of running three 2560x1440 monitors @60Hz?
With both Thunderbolt ports used will it still be able to run a Thunderbolt SSD?
The plan is to use a Henge dock will the Vertical or Horizontal docks work for this?

Some of the concerns with the Macbook Pro is the CPU and RAM. Currently a 2008 8 Core Mac Pro with 14GB RAM and 1TB SSD is being used. Memory pressure is in yellow although the CPU isn't really maxing out.

Option 2: Dual iMac 5K, 1TB SSD, 32GB RAM, i7. I know this will power two additional 2560x1440 displays. The main issue here is scaling.
Will the 5K display using 2560x1440 scaling seamlessly transition open windows between the scaled 5K display and regular 2560x1440 display?
Will there be issues of some programs windows blowing up in size?
Will OS X even allow scaled plus unscaled display?

Option 3: Dual Mac Pros. RAM et all doesn't really matter as all options will run the desired displays. The main issue here is value. This is paying top dollar for a three year old machine. Is it really worth it to run three matching screens?

These options aren't for myself. I'm making a recommendation for a client. All the programs left up, various syncing software, online plus local backups and tons of Chrome tabs (50+) are what is really eating up system resources. My instinct is the MB Pro is the best option. The real concern is that it won't feel much faster than a 2008 8 Core Mac Pro with SATA III SSD and that 16GB of RAM won't be good for more than a couple of years.

The big issue with the desktops besides doubling costs is keeping them in sync over the internet. A high level of synchronization is desired. It must be fast and extremely reliable.

So thoughts. Please no fusion drive recommendations.