I'm upgrading my T3i and need some input. The world beyond Rebel seems more defined or tailored to specific needs and I don't want to grab a camera that isn't suited to mine. What initially pops out at me is it looks as if I'll be able to use my two EF-S lenses on the 1D X as well as my EF lens but I don't see that as confirmed on the Canon website. The Mark III obviously would be more 'portable' and has a much more attractive price. Both are an upgrade to a full-frame sensor but the Mark III is an upgrade in MP as well. I know no one can give me advice from hands-on experience but there is plenty to be read out there and I just can't interpret it all. So perhaps someone who speaks better camera specs than me or has experience with either's predecessor can help me out. Basically, I need something for my portrait work. I shoot maternity, babies, and boudoir mostly on site but I do studio as well. I don't want a camera that will be overkill but I do need the best for what I'm doing.