Hello David(posted 9226 days ago)I started out with 645 and augmented it with a 67 system later. If I could only have one MF system I'll go for the 67. The cost of the lenses for a 67 system is not a lot more than that for the 645. You can kit yourself out for about the same price. If you do not do much fill flash or studio work, that is if you're not bothered by a 30th sec flash sync (there is a leaf shutter 165mm lens available), I recommend the Pentax 67 Mark 2 highly. It handles really well, and the lenses are sharp and fast, . Even if you currently do 11X14 the extra quality and tonality of the 67 film will be worth it.