I'm for the combo if your child is going into the lower of the two grades and the students in the higher grade are functioning somewhere above grade level. That way your child has the advantage of higher level material and the older kids are able to work independently when needed.
We had a K/1 combo when DD started and it was a good compromise as there were no AIG services until 3rd grade.
Its good you have a say on teachers. Around here you don't even get asked.