I had one of the early Noblex 120's which I used for a number of years - sold it and then 2 years ago bought a new one. Both had the slow speed module which I used continually. yes you can change out the filters mid roll without exposing a frame. The close focus capability is another feature I used quite often and will get you in about 3 feet from the subject. I also have had a Linhof 617 and currently have the Canham 617. The Noblex will get you shots which are impossible with the 617's - and with no fall-off of light at the edges. My only complaint is the pre-roll at the lower speeds. It is really not needed to get the drum up to speed. And on the lowest speeds it may creep around for a minute and one half before the exposure begins.