The little Cameradactyl is cute and not very expensive. I think it will also take 2x3 Horseman roll holders, which are said to keep film flatter than Graflex backs. It should also accept Toyo roll holders. Basically anything with notches/slots for Graflok sliders to engage. See, e.g.,
https://mercurycamera.com/backs/com...cks-graflex-mamiya-rb67-horseman-and-mercury/ and
https://1drv.ms/f/s!AggQfcczvHGNmC0J8_On1nsD3l0F
Lenses for the Mamiya Press system have good reputations and are fairly easy to find.
There are, though, other more flexible relatively inexpensive ways to get into 2x3 (2x3 is an abbreviation of 2.25" x 3.25", 6x9 is a poor metric approximation to the format's actual size). Look into the Century Graphic and 2x3 Crown and Pacemaker Speed Graphics. The Century/Crown can use the 35/4.5 Apo-Grandagon, the shortest lens that covers 2x3, but the shortest lens that will work on the 2x3 Pacemaker Speed is probably the 58/5.6 Konica-Hexanon/Omegon for Koni Omega/Rapid Omega cameras. To get an idea of what can be done with these cameras, see
http://www.galerie-photo.com/telechargement/dan-fromm-6x9-lenses-v2-2011-03-29.pdf
If you decide to get a 2x3 Graphic, don't buy a camera without a focusing panel. Too many of the Centuries and 2x3 Crowns on ebay have a roll holder and no focusing panel. This limits them to using only the lens fitted, and then only if the RF is calibrated for that lens. Without a focusing panel focusing other lenses is impossible. That's one of the little Cameradactyl's advantages. Press lenses have focusing scales.