In order to support two 1080i signals to my TV I will need to switch the signals at my AV receiver. So far, with just the HD-XA2 connected the image looks good. Has anybody had to deal with sharing a single component video port on a display with both an HD-XA2 and a Samsung BD-P1200? Are the output levels close enough that I will be able to calibrate once for both players - or will I need to tweak the individual player settings to get a video that works for both input devices?

If I were in your shoes, I'd first find out if both players have video adjustments (I have neither, so can't advise you on this). If only one does, I'd use the non-adjustable player as the "standard", and adjust the other player to match. If both do, then I'd test to see which player gives the best picture on identical source material using its default settings. That will become the standard that you adjust the other player to.