Well, the CMMG I have I can attest is HIGHLY reliable in conjunction with the eley hp subs ... the tacsol I have a highly reliable shooting buddy telling me the tacsol is also very reliable ... and my hope is that with a full gun, that would maximize the reliability. Though all mis-fries with the CMMG have been in snow or rain with a dirty gun. So don't think the lower is a factor, but a matched lower could not make things worse at the very least!
So, I can tell you the CMMG uppers are highly reliable (with the sig 10rd mags and the eley hunting subs).
As to shooting a .22lr from a stand ... that wouldn't work for me ... there are a number of spots within our 5 acre "human area" where the vermin hang out. The wood piles .. the wood shed and the dirt piles ... so I need to patrol about and visit all those locations to get full coverage of all the vermin houses each night I am on vermin patrol. And we have 15 bait boxes deployed across our 7 structures. The bait boxes get an est. 80% of the vermin, I get est. 10% (avg 80 per year) and 10% survive to maintain the population. Before I was doing my thing, our bait box guy was reporting the bait boxes were 100% empty, when he replaced them quarterly. Now he reports a variance of between 50% empty and 100% empty, depending on the box. Also for three years I got about 10 rats in the wood shed. This year I have seen ZERO rats in the wood shed and that is inexplicable. Though I did clean it up and got rid of the tiny twigs we used for starter.
So in my situation I need to move around to cover all the necessary locations. Your situation may differ in those requirements.
As to Coons and Opossum. I get about 20 of those per year, 80% in Nov during the season change ... and I've gotten about half with .22lr and half with 5.56 ... I've found 5.56 can handle with one round whereas .22lr can take up to 8 to get a opossum to fall out of the tree. He might already be dead ... or he might be "playing opossum" ... but I don't stop shooting until I have a non-mover on the ground.
As to coyotes, I wouldn't hesitate to shoot at a coyote with the .22lr, but the opportunity has not presented itself, so all the yotes have been with 5.56 or 7.62. As the vermin population seems to have been reduced in the 5 acre human area, I've shifted the mix of my patrols to heavier guns ... 2 years ago I was 80% .22lr and 20% 5.56 ... now I'm 70% 7.62 15% 5.56 and 15% .22lr though the .22lr gets higher numbers of kills ... in the past 45 days ...50% for the .22lr and most of the rest with the 7.62 ...
