I just set loop points to 1 or 2 measures ahead of where I am going to come in, which gives me plenty of time to get ready.  Then, it will start of playing ahead of the target measure, play through however many measures are in the loop, and will return to playback again - ahead.
 
Wouldn't something like the above give you what you seek now?
 
Bob Bone
 

Bob - as Teksonik said in his post, above:

"Being able to get a count in to get the groove before a drum part starts for example is pretty useful. Yes you can insert empty bars at the start but what if I want to practice from a certain section of the song ? In Reaper I simply hit Play from any part of the song and get a count in......once I've used it I can't live without it........"

The request is more about the ease and versatility of being able to get the count-in for any section of a song. Given tempo changes, breaks, drum rolls etc in the project, I can understand why just a metronome tick at the desired groove would be preferred. That's why I (currently) would be more apt to use record (comping) now to get the metronome count in, and inevitably discard most takes. Would be a nice feature to have.

Got my vote.

Voted. Would love this feature for practising sections that occur right after a tempo or time signature change. Hope they incorporate this idea soon!

IIRC, there is an outstanding bug when loop recording with metronome count-in enabled.  Perhaps the process of implementing this will provide an opportunity fixup this and any other metronome niggles that might be there.

robert_e_bone
I just set loop points to 1 or 2 measures ahead of where I am going to come in, which gives me plenty of time to get ready.  Then, it will start of playing ahead of the target measure, play through however many measures are in the loop, and will return to playback again - ahead.
 
Wouldn't something like the above give you what you seek now?
 
Bob Bone
 

No, otherwise I wouldn't asking for Count In to Playback.  Someone makes the same type of workaround suggestion every time I post this request and no it's not the same. ..........like I said once you use Count in to Playback it becomes very valuable.

Thanks for the positive votes everyone !!