Thanks for all the comments. It is incredibly useful to hear different viewpoints that expand our knowledge of issues we face.
For me, I was advised to, and encouraged by, MOST of the people who responded. My own reasons were simply that, I knew I would fly a lot with my wife, baggage for trips, and preferred a reasonable avionics set up. The thought of an 0-235 struggling with the duty made me want to play it safe and get a beefier motor to help me along. I intend to limit gross weight and am being sensible about CG and fuel loads, but essentially, it just made sense to go the 0-320 route from the get-go. Now all I have to do is finish it! Anyone got a Dynafocal Type 2 mount to spare?? How about a budget transponder?