I am looking at the Groove Clip function. There seem to be a lot of good reasons to use. Any downsides? Why not just use them by default for all clips?
 
And is there any way to do that - set Sonar X3 so that any clip I create is a Groove Clip to start?

None whatsoever in my opinion.  One of the SONAR features I miss when I go into PT and other DAW programs.

Right, its a cool feature with no downside. 

Thanks. So can I make all clips Groove Clips by default.

There's no default setting that I'm aware of to do this.

plincoln
Thanks. So can I make all clips Groove Clips by default.

I think Ctrl-L will make any selected clip a Groove Clip.  You might be able to Select All and convert every clip at the same time. But the clips won't "stretch" properly if they are not exactly the right length.

I would recommend not converting a clip to a groove/acidized clip (they're the same thing) unless you need to change tempo or pitch. And if you do, bear in mind that converting to a groove clip does not always stretch optimally - in fact it rarely does. To me the incredible advantage SONAR offers over all other programs other than Sony Acid is that not only can it can read acidized files (most programs can do that), but after conversion to a groove clip you can edit it for optimal stretching.
 
Some DSP/editing functions don't apply to groove clips. For example you can't use Melodyne on one, you have to convert it back to WAV anyway.
 
Bottom line is I love groove clips and use them all the time, but converting regular clips to groove clips when not necessary won't help, and could hurt.
 

Thanks for all the input.  One more question in this vein. When I go to convert a clip to a Groove Clip I often get asked if I want to 'discard' hidden data beyond the slip edit points? What exactly is the hidden data that I am discarding?

Audio that's beyond the start and/or end points of the audio you've selected to turn into a groove clip.

I love Sonars Groove clipping ( Cntr L ) Sometimes it dosn't work correctly , but for the most part it dose just fine. I also like to bounce to clips after groove clipping on some clips, Thats so that you can Edit the clip at the new BPM ..