Anyone tried the new Geissele MCX trigger in an MCX with the upgraded BCG with the firing pin block?  Specifically curious if it works with the "G" firing pin block.  Not clear whether the "G" block is made for only the normal Geissele triggers like the SSA.  TIA.

Yes, it works great. I can't say I notice much difference between my old Tricon (pre upgrade and pre MCX specific trigger) and the new MCX trigger in terms of function or feel, but I trust Geissele has done the R&D and testing to warrant the change based on their data. Geissele doesn't seem like a company that would disregard  empirical data from testing just to sell me on something . I love my Tricons (lots!) but know that they know more than me.

Thanks.  With that angled top on the MCX trigger, I wasn't sure that it would lift the firing pin block out of the way.

Sig installed a geissele trigger in my MCX during the recall. It's been flawless. 
Not sure what model it is but it's better then the factory trigger but not as good as my Larue MBT

Are you speaking of this trigger?

https://geissele.com/super-mxc-ssa-trigger.html

I just received this and cannot figure out how to install. That trigger bridge fits so snug in the lower it seems impossible to get the trigger past the safety. So...I tried and removed the safety. It works but then you can't get the safety back in. Not sure if I'm just an idiot or what.

I have to say when I did have it in (albeit no safety) and tested it out it was strange. It has 2 resets. One on the disconnector and one on the bridge.

Looking for help if anyone has experience.

Is there any risk of damage running a G2S in a standard AR lower with the MCX upper?

I don't know the full scoop behind why Geissele needed to make a new MCX specific trigger when the G specific firing pin lock works with non MCX Geissele triggers.

Geissele’s take is that a standard trigger will work, but will eventually break due to the high speed of the MCX bolt carrier.  They won’t warranty any of their standard AR triggers in the MCX.  Right or wrong, their new MCX trigger is the only one they will stand behind.

Well that ain't cool. Seems like I need to make another call to SIG asking about a replacement trigger.

I'm curious if it works with both the S and the G models. Would make things a bit simpler.

That’s the one.  No real problems installing in mine.  I dry fitted just the bridge in the lower to check clearances and didn’t have any problems.  It slid in easy, but it wasn’t loose at all.  I found you do have to put the trigger in the bridge first and then put the whole thing in the lower as one unit.  You can’t put the bridge in first and then drop the trigger in from the top because one of “saddles” on the bridge goes more than halfway around the crosstube of the trigger, so the trigger has to be in there first.  Only nit on mine is that the leg on the right hammer spring leg was a little too long.  It’s supposed to lay across the top of the groove in the trigger pin to prevent the trigger pin from walking out, but on mine, the end of the spring got hung up on the bridge.  A few swipes of a file on the end of the spring shortened it so it didn’t get hung up on the bridge.  Kept the safety in for the install.  

I’m not feeling any reset on the bridge on mine.