This is the only one I have used. It's a gamble if you hop or are you saying Id be earning more with my little 2100 Mhash/s in another pool?
I think you'd earn just the same at another pool but your earnings would be more consistent - instead of big earnings one week and little earnings the next week.
I don't think BTCMine is being hopped, and even if they were it wouldn't affect your expected earnings much. But the reward method will increase your variance.