It probably does make sense to break out branch overflow page count and leaf overflow page count. However, it gets complicated to calculate free space if you remove the `Allocs`: 

```go
BranchFree = (page size * (branch page count + branch overflow count)) - BranchInuse
```

I would leave the `Allocs`. They just represent total bytes used for pages and I think it's a simple, useful stat. It shouldn't be tricky to keep track of. It's just changing the `free` and `used` stats you have to `total (alloc)` and `used (inuse)`.