Here are some stats:

```
$ go run quantile_merge.go
Inserting 1048576 items into each of two quantiles
Testing merge performance with 100000 full mergers
Insert1: 281.395831ms (268ns / op)
Insert2: 295.667401ms (281ns / op)
Merge: 4.426840098s (44.268us / op)
```

That was using this code: http://play.golang.org/p/VCeCRDAMey

We could do a weighted average, weighted by the number of samples each channel has.  That is much less mathematically correct and kind of throws our errors out the window.  That being said, we're forced to do that in nsqadmin because we don't have enough information to do a `merge`.

Anyways, I'd **very much** prefer to stay with the merge, but if performance doesn't allow us to then i'll move over.