We raise CX and have tried Rangers as as well. We thought about heritage breeds but honestly they take a long time and more food. Therefore cost was more.
We put our CX in a tractor surrounded by electric fence. These birds are all over the place getting bugs and scratching. they do lay around at times, it's hot here so usually mid-day in the shade. But they are active and not overly massive. We ferment their feed which has helped tremendously for not being stinky. Even their tractor which we move once a week (they sleep there so poop piles up overnight) doesn't smell that bad. We have some that are 14 weeks right now that we're processing this weekend. Most are about 7lbs live weight currently and they run and even fly to the top of the tractor with no issues. This is our second year raising them. 25 last year and 100 this year. No leg issues, no heart issues, no over growing. Ours don't have 24/7 feed after 4 weeks. They get fed about 4 times a day and none overnight. Sure we went longer this time than 8 weeks (we have 3 different ages in the pen) but our feed cost hasn't been bad at all. The ferment helps stretch the feed. Plus we feed them scraps.
The Rangers, they definitely have taken a lot longer and aren't quite as beefier. We will probably stick to CX just because they are the most cost efficient. There was no difference in foraging and activity in our RR and CX. They all were just as active and foraged a ton. We have little CX getting out of our electric fence and free ranging our property. We are fine with it but yea...not lazy birds when given space.
We are happy with the CX for what they are intended to do. We are able to average about 4-5lbs a bird dressed weight and fill our freezer for the year in a short time.