Oren,
If by integration you mean via Rewire,well...having both the Studio One & Reason 4 together on the same PC would be a very dangerous thing!
That being said,I purchased a second computer to keep them separate and anything that I will add from Reason 4 to the Studio one,will be in the form of a WAV file(I like things simple as possible).
As a matter of fact,I won't even be plugging in my Korg M3 directly into my Presonus Studio One,because the Korg is a bit too bulky & complex for my situation,so again,converting everything from the Korg to WAV,is the way to go(for me).
Thanks for the kind accolades dude!
-Thom