I have Samplitude Pro X3, and I've been seriously digging into it over these last few days, since I might was well start with an alternate DAW I own, rather than pay out for one I don't. It's a very powerful DAW, definitely underrated, as Larry mentioned. It's audio abilities are outstanding, and so far the midi tools are solid, although it has different ways of doing some things, and its going to take me some time to adjust. Sonar is still way easier to use for some midi stuff (routing midi audio, bouncing takes, etc), and in a few other areas. I'm finding things like signal routing and track bouncing to be challenging in Samplitude.
So, this is early days with Samplitude and no doubt I'll have a different perspective after spending more time getting to know it, but for what it is worth, these are my current impressions:
PROS:
a) Mature and stable, I've had no issues with crashes or bugs of any kind
b) Comes with a nice library of samples - synths, pads, full version of Independence, plus cinematic percussion, choir, folks instruments, etc. All very useable and a nice bonus
c) Samplitude's built in plugins seem quite nice and do the job pretty well
d) Midi editing tools are solid and easy to use. The PRV, which is where I live when I'm recording, is well laid out and intuitive and has all the tools I regularly use.
CONS:
a) I'm not entirely keen on the interface (although I've seen worse). Its not the most clear to read, and the colors are drab and sometimes make it tricky to differentiate what's on screen.
b) I'm trying to figure out signal routing, and I feel like I'm banging my head against a wall. Part of that is just unfamiliarity on my part, rather than a deficiency in the DAW, but for folks pondering a switch, I think its a factor worth thinking about. It is definitely a different program than Sonar.
THINGS STILL TO BE EXPLORED:
a) I'm trying to figure out how configurable the menus are and, in particular, the layout and setup of the VSTs and effects. Sonar is so wonderfully configurable, in this regard...
b) All of its audio-editing features. I've been dealing mainly with midi, so far
c) The quality of support from Magix, and the nature of the Samplitude forum. I introduced myself there last week, and folks seem nice, but it certainly isn't the humming beehive of activity that is Sonar's forum.
There is no question that Samplitude will do everything you need it to, and its very powerful and full featured. But how comfortable I will be using it, is still to be decided.