I've only just noticed that when you're helping someone mine, they get the ore bonus but you do not. I just think it would be nice if the helper also got the +1 (or however cumulative the bonus may be) for all people being helped.
As an example, the way things are now 2 miners are mining a single sparkly ore with the same level of mining. Miner A starts, and Miner B helps. Miner A gets +1 ore added to what he would already get, while Miner B gets nothing. Miner A finishes first, then Miner B finishes. Miner A starts mining, and repeat, meaning that Miner B gets nothing for helping Miner A, while Miner A reaps all the benefits.
It's not going to always happen, but it is annoying when it does or when you're the last person to mine a rock before it is depleted so you get nothing for giving everyone X bonus ore. Not to mention that it means that the bonus for actually being a helper drops off more and more the later you join in. I just think it would be nice to get some sort of bonus for actually participating.