I haven't kept either species, but I expect the BRB enclosure would have higher humidity than would be ideal for a BP, and I think that would help break stuff down quickly. My enclosures have just enough moisture to keep the plants going, and while there is compost in the mix, there doesn't seem to be much active composting going on (not like a compost pile or worm bin, anyway). Also, the layers I've used are fairly thin. The leica "false bottom" drainage layer was laid down at 1 1/2 inches, and the growing substrate was originally 3-4 inches, but has since packed down/broken down a bit. (Slither Seeker, I am not trying to cut anyone down if that is how it came across. I just wanted to provide helpful advice based on my own experience. You obviously know what you are doing!)
Smell to me, is the best indicator if spot cleaning is needed. If the viv is stinky, I start searching for the source. If it smells fresh and woodsey, I don't worry about it.
Both of my tanks started with similar materials and plants, but they developed very differently. I think that is part of the fun of them.