Hi
The way PT 11 handles VI's are much different from Logic and Cubase. I have been testing all 3 - and DP8 + Studio One - for a very long time. No question I think that Logic X is a master in economizing with the resources, so you can get the smallest buffer and latency. But as you mentioned Logic X is not the choice if you want to use VEPro on another Mac or PC, because the routing is chaotic.
I have gone with Cubase 8 although there for the moment are some problems with the Asio Guard feature when you are using VEPro - I think! I think the possibilities in Cubase are very good and you can have all the extra stuff, like VCA faders, compression showing in the mixer, soloing effect tracks and the best midi-editor.
Even with buffer size on 128 samples my project runs fine with Asio Guard 2 turned on in the small position.
The only drawback for me is that Cubase doesn't fully support the Eucon, so my to Avid Artist controllers is only used for volume. 
Now you write that PT11 only deals with the Midi, don't you stream the audio back into PT11?
If you ask wich DAW is best, I think you will get a lot of different answers, but take a look at http://www.vi-control.net, I think it can help you.
Musicmind (Mind the Music!)
Mac Studio Max 64Gb, PC Slave 64gb, Mac Pro 12 48Gb, MacBookPro, Apollo interface, Universal Audio, Waves 9, NI Komplete 9, VSL, BFD3, Superior, Arturia, Sound Toys, Euphonix MC Mix, Neumann mics, DynAudio, Yamaha + Adam monitors AND Steinway Concert Grand A ;-)