First of all, if you don't have an old player file that you want to continue with, you want to:
1) Run JtRH and create a new player.
2) Click the Export button on the Change Player screen and save a .player file.
3) Run TCB and import that .player file instead of creating a different new player.
That puts you in a situation where you can transfer holds and saved games and stuff from JtRH to TCB and the game will still treat them as yours -- there's an internal player ID that would be different if you just create a new player in each game.
If you do have an old player file, import it into both games now.
Once that's sorted, onto the holds:
The KDD 2.0 hold can be imported into either the JtRH or TCB engines. It'll end up with different styles/music in each engine, but it mostly comes down to personal preference. If you want the experience you would have had from buying KDD 2.0 as a full game, play it in the JtRH engine.
The JtRH hold can also be played in either engine, but with a catch. It can be played in your copy of the JtRH engine right now, of course. Or if you purchase a CaravelNet membership then a revised version of the hold will be available for download in the TCB engine, which uses the additional styles and lighting effects in the new engine (and has the TCB engine music instead of the JtRH engine music). Again, mostly personal preference (and if you weren't otherwise interested in CaravelNet, whether you think it's worth $12 for some pretty lighting...).
The TCB hold, of course, needs to be played in the TCB game.
Personally, I'd vote for playing both KDD and JtRH in the JtRH engine. It just feels right somehow.
Note that at any point, you can do another full export from the JtRH Change Player screen and import that file into TCB, and TCB will merge your progress. So if you start playing a hold in the JtRH engine, you can carry your game straight into the same hold in the TCB engine. That doesn't necessarily make a lot of sense when you're doing the initial playthrough, but it means you can end up with all your saves and demos in once place (the TCB engine) at the end. Note that the import only brings in saves for a hold if it's already installed in the TCB engine at the time of import (but you can install more holds and re-import the player file as often as you need to).
As a final side-thought, there's at least one user-made hold ("
The Fool's Errand"
) which is best experienced in the JtRH engine, not TCB. There might be others but I'm not aware of them. Again, you can do the initial playthrough in the JtRH engine and then transfer your progress to the TCB engine for completeness.
[Last edited by Tuttle at 06-13-2010 03:08 PM]