Sorry, overlooked the part where you needed to overlay a logo
Enquire with
http://svconline.com/mag/avinstall_chyron_chytv/
They may have come out with a better than composite video box since.
Then again, you would also need a multi-res matrix 4x4 matrix switcher to assign the logo to the 3 other outputs.
An alternative is a 4th pc with one Blackmagic Design I/O cards that allow you to key grahics over anything.
Costs and complications mount as you add all these things.
I'd recommend AvStumpfl's Wings Platinum Multidisplay version. With version 4 of the software, they have a 2-, 3- and 4-output per pc versions, something which Dataton does not have. To elaborate, Dataton requires the Master PC to run only the Master Controller program, and the Display PCs to run the displays, in your case 4 licences with 4 PCs to output to 3 displays (where'd you get the figure '9' from?). In AvStumpl's case, with the 2-output version of Wings 4, you only need 2 licences and 2 PCs to output to 3 displays 'cos the Master can run both the Controller program AND one of the displayed outputs (using the secondary output of a dual-display graphics card), and the one Slave PC can output to 2 displays using both outputs of a dual-display graphics card.
With multiple layers in the timeline, you can then overlay your logo over all 3 individual displays without extra hardware and complicated connections.
Needless to say, since you intend to use 1080 file res, the PCs and graphics cards must be up to the task, especially when asking the Slave PC to output 2x1080 files without a hiccup. Not impossible with today's hardware offerings.
Price? Varies between countries. Ask the dealer/distributor of your country. But I dare say, AvStumpfl's per pc licence key for the Multidisplay version is lower than Dataton's.
I'm using their version 3, bought when the Euro was much higher than today. Having said that, Dataton does have a Starter Pack at a lower than individually-purchased price which comprises of 4 licence keys, good enough for 1 Master and 3 Displays.