I may rarely print a 4"x6" print any more. I usually go from contact print of the roll of film directly to 8"x10" or 11"x14" directly. Now I almost always print 11"x14". When I get larger trays, I will probably print 16"x20" much of the time. Therefore I would not be interested in you device.
I am sure that others will disagree with me so YMMV.