While evaluating MongoDB, I tried to insert into a single replica set (one master, two slaves) many small documents (around 100 GB of data) with eight Python clients.
I kept the default oplog size, which is between 5 and 10% of the whole disk. It doesn't really matter, since it can only delay the problem without really avoiding it (in case of permanent insertions).

Before the end of the import, I got the evil RS 102 error, too stale to catch up. I can understand this, since the master has to spread all the data it got to two (or more) slaves, so slaves are slower than it.
However, can I expect a new configuration option to force the master to wait its slaves before reaching the non-return point?

Thus we could ensure that this RS 102 error will not happen anymore.