I have used a negatrans. I did not myself experience any scratching. I believe they are useable without the glass..its has been 30 years since I have owned one. They come in different models for the 23 and 45 series is my recollection.
I believe that most anything that speeds the handling of negative and allowing quick orinting of frames seems to lead to a quality reduction for printing. Printing should be contemplative.
A good double glass carrier is a good investment I believe.