I have a Gisselle SD3G trigger for my carbine and really love it. For a bullseye/hole puncher/precision type of setup, which 2-stage trigger do you prefer?

SDE

Mucho happy with my MBT flat bow.

This. I just got mine in a few days ago. I can’t believe that this quality of a trigger is $90 out the door.

Depends on what your use-case is. I like TriggerTech Diamond for precision and it can be adjusted to super light pull or heavier pull. The adjustments have detents so no loctite is required. Cleanest break of any trigger I've ever used, however it has a very very very chill reset. Tactile, but not super "forward". Think of a mouse click.  Hard to explain. My MBT2s is pretty good if you don't want to dish out the money for a TriggerTech. For 2-stage, this would be my second option. I put a yellow JP spring in the 2s and it reduces the weight to 2.5ish lbs.

Overall, TriggerTech has the best trigger I've ever used. I have a CMC, Elftmann 3g, Geissele SD3G, POF 4.5, Hyperfire PDI, and a few others.

I've got an SD-E and a MBT-2S for my two stages.  I like them both but it's hard to pass on an MBT-2S for the price.

Same

I just ordered the MBT 2S flat trigger. Thanks for the recommendations!

Any concerns with using this on an HD rifle? I have one but have yet to install it. Since it's a bit more complex than a GI trigger, I'm worried it would be more prone to issues when dirty.

I have the MBT-2S flat bow, Giessele SD-C and TRI-CON trigger. All are flat bow with the exception of the TRI-CON which is a "hybrid" according to Giessele. In practical application I feel very little difference between the 3. I don't spend a bunch of time or devote a bunch of thought towards what my finger feels like on the trigger but I do notice the feel of the trigger when I'm actually using it. With all that I can highly recommended the MBT-2S because of the price, quality and function. At less than half the retail price of a comparable G trigger the minor difference in the feel of the trigger as you pull through may not be worth the extra money to you. I have all these because I wanted to see for myself what differences there were between them and I can honestly tell you they all function as they should and do so very well. The Larue probably required a little bit more break-in from brand new. It felt a little coarse to begin with but after a few hundred rounds during my first range trip it smoothed out. I use a dab of Aeroshell grease on all my triggers when new and occasionally after that. I absolutely love the Giesseles but I won't be replacing the Larue any time soon. Hope this is helpful.