In conjunction with the "First N% of Rows" and "Group by column (optional)" features, an additional option that would be great to have would be to tell the tool to take at least 1 record per group. If I am telling the tool to take the first 3% of records and grouping by a field, but one of the groups only has 5 records, it won't return any records for that group, as 3% of 5 is .15, so the tool rounds that down to 0. If I could also choose an option for the tool to always round up, that would also be sufficient.