You own a Contax camera system with a Phase One P30 back right.
It all depends on your experience.
I find my dealings with equipment to be 180 degrees from yours.
My and many other peoples problems were with Phase One AF And DF cameras ... I've told you before. maybe that's why your experience is different.
Regarding your back... I've said it before... the P series backs are nice backs, built like little tanks and really quite nice an simple.
However the most important point is that a picture is worth a thousand words... a side by side comparison is worth even more.
Here is a side by side comparison between a D800 and a 40mp medium format camera:http://www.luminous-landscape.com/forum/index.php?action=dlattach;topic=69391.0;attach=64261;image
For me it's clear as day.... 35mm DSLR D800 matches 40MP MF DSLR quality. I prefer the rest about the camera, the workflow, the ergonomics, way bigger choice of lenses, image stabilization, way better live view, wireless/wired tethering, video, much stronger company and all this is a simple "over the counter purchase"... no need for a value added dealer to hold my hand throughout the whole thing.
As far as bigger formats go... I'll skip MF Digital because it looks the same as the D800 and I'll rather go to 6x8cm and 8x10 film for totally different looks.
Use 50s Adox formulations, 8x10 paper negatives, traditional post. etc.