I have a 2005 and a 2007, and both use some oil between changes. I sent the oil from the 2005 in for analysis, and the oil consumption isn't based on wear. Because it seems to be related to load when driving, and because the car that was beat on a little more (2007) uses more, my guess is that it's from plugged oil return holes in the pistons/sticky oil rings. The 2ZR-FE had a TSB for it, so I wouldn't be surprised to see it on other engines.
http://www.rav4world.com/tsb/2011/T-SB-0094-11.pdf
Knock on wood, my wife's plug-in Prius doesn't burn a drop of oil with ~12k-15k OCIs (~10k-12k on gas). My feeling is it won't be an issue as long as I use a decent synthetic and don't go too long between oil changes.
In terms of quality, the 2005 is better than the 2007, but that's mostly because it's a higher trim level (V versus III) and because it's been treated better.