Jim, I just went through this process earlier this year. I evaluated the 350, 320, EX1R, and the EX3, finally settling on the EX1R. OTOH – I know several outstanding DPs (including Rick Diamond) who are also very smart equipment-wise, who chose the EX3. I almost chose the 350 (2/3″ sensor, better lens, feathered zooms, better hand-held configuration) but the added weight and price sent me to the EX1R/EX3. The 320 – 1/2″ sensor – why bother? I finally chose the EX1R over the EX3 mostly due to a conversation I had with a repairman who’s seen a lot of broken EX3 viewfinders. I like the way the EX1R’s viewfinder tucks safely into the handle.
otoh – Feathered zooms are hard to do with the supplied lens (which can’t be replaced on the EX1R but can be on the EX3).
After reading a lot of horror stories on this forum about the SD cards, I went the SxS route. Again, YMMV– many excellent shooters have no problems with the SD cards.
Good luck. You are entering the HD world with many, many great choices, none of them bad. You’ll be very happy with the quality, but you also need to think about how to deal with tapeless archiving.
Bob C