I thought about implementing other pairs, but I simply think there won't be too much depth and volume on these to make it worth it.

Can you elaborate on trustworthiness ? BTC-E has been there for long now that's true, but I heard a lot of complaining about their support, and deposits are often delayed (in my experience too).

The other exchanges out there are not much more trustworthy in my opinion, in the end you rely on the guy running it.