I've made the step from 5 to 6 this year. Before, I liked Reason, but a major disappointment was definitely the fact that I couldn't record in it. You had to have record than at that point and the idea of needing two programs to do what I want didn't appeal to me in any way. Than they launched
Reason 6 and I started reading up on it , checking the Props site and youtubes and I was really appealed by it. I finally bought 6 this year and I'm really content with it.
Reason always gave me a feel of being a real musician instead of a computer engineer. Next to that, the creativeness and the sound design are something in Reason that I think isn't around in any other DAW.
If you're used to Reason and know a lot about it, I wouldn't make the switch to something else tbh. Stay with Reason, it has everything you need, if you have the know how that is. Musical theory and you need to know how to work Reason. Also, the guys at Propellerhead are so close to their clientele. Also, the tutorials they put online, the stuff they organize every year, etc. That's something on the side you get that's so valuable as well.
If you liked
Reason 5 and you're not one of those Reason haters who's gonna ***** about vsts not being in it, not understanding it, not understanding how to work an SSL and proper sound engineering techniques and all of that, you definitely should get Reason 6.
With the rack extensions there, that probably means all of your favorite vsts are gonna be made for Reason. Although, the need fof vsts in Reason is debatable, but having more instruments and effects made by pros in the business doesn't hurt in any way.
With Reason 6 they combined Record and Reason into one which finally made it a full on DAW in my opinion.
I wouldn't doubt a second on what to get and the features you're looking for are well within Reason 6. No need to make a switch and all that Reason knowledge is gonna let you grow more instead of needing to learn another DAW. Other than that, Reason 6 is perfectly capable to be used on it's own without anything else. No need for vsts or other DAWs to rewire it with. Of course, you can always choose to do so, but to make quality music, you don't per se need to!