Barret, re grip shifters-as you say that you have used them and are happy with them, this may be a moot point-but I have always found that grip shifters to be a pain when wanting to shift and to keep a good, even grip on the bars. Much much prefer the snick snick of triggers while keeping your palms securely on the bars if the surface is iffy or whatever.
On top of that, I was quite disappointed with the grip shifters on my wifes Specialized Vita (I imagine they are very middle of the road level shifters) as they began to develop problems and a local mechanic confirmed my opinion by saying how he sees grip shifters with issues, whereas triggers tend to go and go and go.

As I said, component level must play a big part, but for me the "ergonomics" of shifting in rough terrain and having to change your hand pressure on the bars to grip the grip, is the real deal breaker for me. I bring this up mostly as when one thinks of trekking bars, I think of the good likelihood of being on rough roads and wanting as much front end control as you can have.

The other big advantage of trekking bars I see is that your shifters are really in a protected area (for not getting whacked in a fall, or with manhandling) and so while I tend to feel that medium high components last quite well, they would even be more long lasting as the bars would protect them so much more. Mechanics I trust at one of my LBS have told me that mid range triggers would work just as well as the originals on my 98 Rockhopper, which while still working great, will get replaced at some point (I am touching wood right now) and I dont see the need for high end ones.

anyway, just more 2 cents worth of opinions.
cheers

oh, what crank are you thinking of putting on it?