This works fine with result sets up to around 16KB. I notice that BsonBuffer.chunkSize is set to 16KB, seems likely to be related? See the following stack trace issued when trying to create a new list from a FindAll query:

[EndOfStreamException: Not enough input bytes available]
MongoDB.BsonLibrary.IO.BsonBuffer.EnsureDataAvailable(Int32 needed) +159
MongoDB.BsonLibrary.IO.BsonBuffer.ReadString() +217
MongoDB.BsonLibrary.IO.BsonBinaryReader.ReadString(String& name) +299
MongoDB.BsonLibrary.BsonElement.ReadFrom(BsonReader bsonReader, BsonElement& element) +422
MongoDB.BsonLibrary.BsonDocument.Deserialize(BsonReader bsonReader) +111
MongoDB.BsonLibrary.BsonDocument.ReadFrom(BsonReader bsonReader) +119
MongoDB.BsonLibrary.BsonElement.ReadFrom(BsonReader bsonReader, BsonElement& element) +550
MongoDB.BsonLibrary.BsonDocument.Deserialize(BsonReader bsonReader) +111
MongoDB.BsonLibrary.BsonDocument.ReadFrom(BsonReader bsonReader) +119
MongoDB.BsonLibrary.BsonElement.ReadFrom(BsonReader bsonReader, BsonElement& element) +550
MongoDB.BsonLibrary.BsonDocument.Deserialize(BsonReader bsonReader) +111
MongoDB.BsonLibrary.BsonDocument.ReadFrom(BsonReader bsonReader) +119
MongoDB.BsonLibrary.Serialization.BsonSerializer.Deserialize(BsonReader bsonReader, Type type) +130
MongoDB.BsonLibrary.Serialization.BsonSerializer.Deserialize(BsonReader bsonReader) +110
MongoDB.CSharpDriver.Internal.MongoReplyMessage`1.ReadFrom(BsonBuffer buffer) +1119
MongoDB.CSharpDriver.Internal.MongoConnection.ReceiveMessage() +470
MongoDB.CSharpDriver.MongoCursorEnumerator.GetReply(MongoRequestMessage message) +262
MongoDB.CSharpDriver.MongoCursorEnumerator.GetFirst() +937
MongoDB.CSharpDriver.MongoCursorEnumerator.MoveNext() +260
System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +472