I pre-ordered a 1Dx last year but the 5D MkIII became available first and I went for it instead and cancelled my 1Dx pre-order (I couldn't afford to buy both). Ever since, I've had the feeling that I missed a once in a lifetime opportunity. I'd swap my 5D MkIII for a 1Dx in a heartbeat, but unfortunately my current financial situation won't now allow it. I prefer the 1D form factor, so if another opportunity should arise, I'd definitely choose a 1D over a 5D. Another lesson I learned was NOT to be an early adopter ... apart from any technical issues, I could have saved myself almost £1000 if I could have waited (subsequent price drop plus Canon cash back).