Well, me too.
I was a UA 1K when CM and UA shared the MileagePlus program, and it was great. Then they separated, and I'm stuck between the two programs, with mediocre status on UA, gifted Presidential Platinum status for a couple of years on CM. But I have tried to get behind CM in full, but have suffered. I realized my typical annual travels get me, at best, Gold status on CM. I already have a ConnectMiles credit card from a Panamanian bank that gives me Silver status. (The yearly fee is almost $150 and can be a pain in the rear to use.)I fly a bunch of 2-3 hr flights out of PTY. And I fly occasionally 5 or 6 hour trips. I love the upgrades on the 3hr flights... but when I really really wanted an upgrade to EZE, I couldn't get it, no matter how many miles or upgrade certificates I wanted to use. Two years of ConnectMiles upgrade certificates were completely useless to me, zero usage due to restrictions and unavailability. But I almost always get upgrades for the short flights. So it's a big debate for me.
I typically use miles to gift flights for relatives and friends. I find no difference between using UA miles and CM miles for the flights that I typically look for.I think I am going to credit all my CM flying to MileagePlus this year, and give up on ConnectMiles. I can afford to sit in Y for those flights to Bogota and Lima (free snack and a drink regardless), to achieve better status on UA for flights to the US and beyond.
As far as "serious ConnectMiles" flyer, I can offer a colleague. He gets Pres Plat status by virtue of segments. He buzzes all over Central America, several flights a week, and because of last-minute fares and upgrades, gets 2 segments per flight to hit 95 segments. As I have posted elsewhere here, I can't imagine how many more serious CM flyers exist, except for the passenger buying J PTY-LAX or JFK once a month or more.