Bitcoin doesn't require all winning blocks to be sent over I2P, thus in a high-latency setup, those miners who want their awarded coins to be anonymous, would be at a timing disadvantage.
I assume anoncoin requires all winning blocks to be sent over I2P?
nope, you can send it over i2p, TOR (to clearnet or HS nodes) and clearnet. the main idea about i2p in anoncoin is to eliminate attacks to find your location and making listening on others connections impossible. (from a technical view)