X1 is a bit cramped in the rear (not much bigger than the previous gen 3 series). The trunk is smallish so once a stroller goes in there, you don't have a lot of room left (X3 has a bit more cargo room, but not much). The X1 does not have vents in the rear (not sure if that matters to you)
Also, given that the X1 is E90 based, it rides a lot stiffer... will baby be comfortable with a rock hard suspension?
I see that you're already looking at the larger Q5 .. so give the X3 a shot (it is cheaper than the audi still). The Tiguan is probably in a similar size class as the X1.
My wife and I are pretty much decided on getting another X3 as well .. but if you want another option, take a look at the 2013 RDX V6.. equivalent size, cheaper than the X3, more power and way more comfortable (uses some kind of specially valved adaptive dampeners)
F25 X3 N20:
2010 B8 A4 2.0T quattro (current)/
2013 F25 X3 x28 N20 (babymobile)