I'm coming back to update this thread since these rifles are pretty common, and I think a lot of people are looking for trigger information. I tried both the MCARBO spring and the Timney 603 trigger in my X-Bolt Pro this year.
Unfortunately, the MCARBO spring was disappointing. The instructional video shows a pull weight of approximately 2.5 lbs with two threads of the adjustment screw exposed, but my rifle measured closer to 4.5 lbs. I had to back out the screw until barely one thread was engaged, and the lowest measurements were just under 3 lbs. This was less than ideal because then I had to worry about the screw falling out. Also, the spring did not fix the poor feel of the Browning trigger.
I posted this review on MCARBO's website in May, and now it seems to have disappeared. This might explain their 4.94/5.00 stars if they are actively removing low ratings.
I was hesitant to install the Timney 603 trigger for two reasons. First, some of the prior reviews on MidwayUSA and on Timney's website indicated that there were interference issues with the stock, but I did not find this to be true with my 2019 X-bolt Pro. No modifications were required.
Secondly, the factory trigger group locks the bolt closed when the safety is engaged, and Browning includes a button on the bolt handle that allows you to open it while keeping the safety engaged. The Timney trigger is not compatible with this button (as noted above in this thread). After installing the Timney trigger, the bolt does not stay locked closed if the safety is engaged. The bolt is free to open, which could allow it to come out of battery while hiking around the woods. In the end, I decided that the improved trigger was worth losing the bolt locking functionality. Lastly, Timney does not allow you to post a review on their website unless you purchase direct from them.
Attached is a photo of the two trigger groups (Browning vs. Timney).