This might be some hardcore BFD2 geekery on my part, but here's some food for thought:
1. Get a basic drum part together in Sonar
2. Use the Sonar PRV for writing most, if not all, of your drum parts and editing velocities
3. Export the track as a MIDI file in Sonar (and mute the MIDI clip on the track)
4. Import the MIDI file in BFD2's groove player
5. Copy that groove to the Drum Track (be sure to set BFD2 to play the Drum Track)
Now why did I just do this? BFD2's internal timing is much higher than the 960PPQ that Sonar/MIDI can offer. So internally, there's a lot of room for subtle variation on timing once you get the track in BFD2. There's another reason which I'll get to...
6. Now use BFD2's groove controls to edit the timing, humanization, weight, and compression of the MIDI track until your performance is right
Again, the added resolution offered by BFD2 along with the quick access to the groove knobs make humanizing drum parts a breeze. Now that our drum track sounds human...
7. Set all your volume faders in BFD2 to 0 and pans to center (turn off any effects you're not 100% sure about either)
8. Arm all channels in the BFD2 mixer that you intend on using for your drum mix
9. Export to audio directly from BFD2's mixer
10. Archive the BFD2 track (and hide it from the Track View and PRV to avoid clutter)
11. Import your new audio tracks from the BFD2 export as new tracks in Sonar
Now, why did I just do all this? A few reasons: first, I want to have my drum tracks printed to audio unmixed. This way, 10 years from now, if I need to recall a mix, I have the audio even if BFD2 is no longer compatible with whatever future DAW or plugin format I'm using. Plus, if I'm working with or for other people, then they can take the drums as audio to get the track remixed if needed (I'll also provide the MIDI). I find it's generally a good practice to give them everything anyway.
In addition to that: BFD2 does some internal velocity randomization with Anti-Machine Gun mode (AMG) on. So if you were to do the bouncing in Sonar, kick layer 29 might get triggered on bounce one (Kick In), but layer 30 might get triggered on the second bounce (Kick Out), and by the time you get to the overheads, maybe kick layer 28 will get triggered. If this were to happen, you'd get some weird flamming on the drums and potential phase issues. This drives me nuts about Sonar! Why can't it do just one bounce for all outputs?
Also, while I love the BFD2 mixer and the effects are superb, I prefer to mix the drums in Sonar. I might use keep the CompChannel (1176) effect on a kick or snare as needed, but most times, I'll use VST plugins on the audio for the drum mix. Plugins include Slate's VTM into VCC, then either a UAD 1176 Collection comp on snare or kick, some EQ (usually DMGaudio), a Valhalla verb on Snare and/or OH's, along with a Cytomic The Glue on the drum buss and a buss EQ for some air.
Last reason to do this: it takes a lot of pressure off your hard drive. Why? Because every time you start riding the ride in BFD2 you're triggering multiple samples as one ride is still fading out while another comes in, then factor in all the other drums and the other mics and that's a lot of stress on a hard drive. You might be streaming more channels of audio at a given time than you realize. If you don't have a dedicated BFD2 drive, you could start choking up. So I bounce out of BFD2.
Ultimately this leaves me with about 12 audio tracks I can mix in Sonar like I can mix like drums I recorded myself, sound human, and can recall years from now with no issues because I mixed them down to audio. Do I do this all the time? No. Only on the rare occasions when I finish one of my own songs, or mix/record for someone else. But when I do, it's worth the extra effort IMO.
Sorry for the giant post.