The difference between the backs is something is really what you are shooting overall performance versus value the P25 plus is it. The P30 plus is suited to people work and it does a damn good job of it but it is a crop sensor and you really cannot use it for swings and tilt work so it does have it's limitations but ISO speed and such it is a tough act to beat. The P45 plus has the best micro detail among the Phase backs , these folks actually market there products correctly and tell you exactly what each one is good for and there actually quite correct. I like what I have seen and happy with my choice although I have not tested the Sinar, Hassy and Aptus which i am sure some of them are very good indeed. This just make sense for me at this time. I loved MF from my Hassy days and it sure is a kick shooting it again. I totally had a blast shooting these models today in under the gun pressure.