While not nearly as researched on 2nd gens, your local toyota dealership isn't entirely off base. The later model, I believe 2010/11 and up, 2az-fe has a higher compression ratio, higher redline, more aggressive cam profile and piston oil squirters, based off wiki to start and then browsing through various parts catalogs. The 2010 and up have different part numbers than the 2008-10 models, including but not limited to the cylinder head and block.
I know the issue with the earlier 2az's is the pistons and rings, causing excessive oil consumption which you stated, regarded in toyota's TSB(which lists only US rav4, camry, solara but go ask any gen1 TC owner about it and its pretty much the same problem). Changing the pistons and rings out would be slightly less involved than pulling the whole engine. Unfortunately, I can really only speculate as to whether they would be interchangeable without knowing more about the engine components and wiring harness. Best case is that they are, with very little or no modification necessary. Worst case, you'll likely need the 2012-13 engine, ecm and harness.
It's not much, but I hope it helps.