Gary,
My secret weapon is to actually use a piece of triggering software before I apply the transient markers.  For this I use Slate Audio Trigger.  I bought it because I thought it would be the end-all be-all for drum replacing.  I haven't had a ton of luck with it.
 
I often use my own samples, and it's much easier to use session drummer than create whatever I need to create for my triggering software with my own samples.
 
I do, however, use Trigger a lot for room sounds because my room isn't that big.
 
Anyways, here's my process:
1. Apply Trigger and make sure everything's triggering correctly.
2. Freeze the track.
3. Copy the new frozen clip to a new track (otherwise copied transients in step 5 will also include the ones of the original track.  Lame.
4.  Enable Audiosnap.  Go over the entire track and make sure everything is triggered properly. (no false, early, un-triggered flams, etc).
5.  Copy n paste to session drummer.
 
Somewhat long process, but it works for using my own samples the way I want... so I do it.

I'm wondering if the Transient Shaper might be better than a Gate for defining the hits in that process. Sounds like it's catching the front end of the hit just as the gate is opening up instead of the meat of the hit.