I've been clamoring for this for about five versions now. It'll happen eventually, once something passes the ubiquity point it just becomes mandatory. I suspect they're putting it off because it will require a major engine rewrite. But who knows, maybe it'll be a great time to revamp Audiosnap and such.
 
And yes, agree with the OP, Reaper, as problematic as it is, has a pretty excellent implementation of this. Per project, AND per clip playback rate variation. Mmmm mmmm
 

southpaw3473
I have requested it for a long time as well. For me, in the old analog tape days, I used it to bring acoustic instruments in tune with other tracks. Bagpipes, bombards, fixed tone flutes and many other instruments are very often not in concert pitch. By altering the tape speed you can bring those into tune.
 
I used to have a Yamaha AW-4416 digital standalone workstation and it had a vari-speed that simply decreased or increased the sample rate. Change the sample rate/track the pesky instrument/change the sample rate back. Worked like a charm. It was the single biggest thing I missed when I switched over to Sonar. 
 
For me, Melodyne or other pitch correction often takes some of the unique timbres of exotic acoustic instruments.

I'm not sure how that would work in a multi track DAW. All the ones that do vari-speed do it to all the tracks not just one. Perhaps I don't know how it works in other DAWs because I have not use it in any other DAW except to check it out once a long time ago. I also have Sound Forge and it can do it to a track. 

I'd like to see this as well. Actually I'd like to see a "vari-speed+" ... combine it with the requests for an easy audio stretch.

I'd dig it!

Lynn
I would like to have vari-speed, too.  There are many creative uses for this other than the obvious.  Yet, I can see the challenge in this, considering that it involves time and pitch stretching.  I'm just curious to know exactly how well it works in other DAWs, i.e., is it flawless?

No stretching is "flawless." What works best is changing pitch via resampling without preserving length (which of course also changes the timbre), or transposing by only a small amount if you want to preserve length. The more the stretch, the worse it sounds; also, speeding up is far better than slowing down. With speeding up you take stuff out, while with slowing down you have to create audio that wasn't there in the first place. The perceived quality of stretching also depends on the program material.
 
Offline stretching algorithms are much better than real-time ones, and the iZotope one in Sonar is about as good as it gets. zplane also does good stretching algorithms although I'd give a slight edge to iZotope.
 
This is why I detailed the workarounds above. They do the best job of preserving audio quality, which is very important to me, and accomplish the two main uses for vari-speed we did with tape back in the day.
 
 

I would also appreciate this feature... and have requested for quite awhile.  Maybe it will happen soon.
 
Jim
 
 

Check out Lindsey Buckingham's use of vari-speed on many of his guitar parts. Awesome!
 

Sounds like a nice idea. But I want the meat and potatoes features first...!

rodreb
Check out Lindsey Buckingham's use of vari-speed on many of his guitar parts. Awesome!

He also uses "Nashville tuning" to get some of those "jangly" guitar sounds.

Two words Craig: THE. BEATLES.
 
I did a slowed down vocal and just dumped the mix into reaper, sped it up, sang to it, then returned it to normal and bounced it back out and brought it back into SONAR. Sounded amazing.