I'd like to start a project like this too but I'm kinda unsure as to the transition of submersed to immersed and back again.
I've transitioned most of my crypts from submersed. They look pretty pitiful for a while but the growth seems to have sped up.
I've mostly transitioned plants from emersed to submersed when purchasing plants. These also have a ton of stress from shipping most of the time added into the mix too. I know some plants suffer from the transition more then others. I recently planted emersed Bacopa caroliniana into my 2.5 gallon vase. It made the transition to submersed smoothly with no issues at all.
I'm expanding my set up with the hopes of keeping a large variety of Cryptocoryne species. The real goal for me is to get the plants to flower!