In particular, the NXLV format still needs work;
What is missing there? As far as I can tell from the file parser, all properties of objects, terrain pieces and the level itself can be set in the current NXLV format.
...and the new graphic set format will be a huge hassle to use in conjunction with LVL format levels.
Are there further problems apart from having to translate the old piece names into the new ones? And I thought this problem is solved via the translation files .nxtt in the folder styles/translation?
Then, given the intention to move away from NXPs in favor of folder structures, this also means there's a need for overhauling so that the game doesn't rely on the "load one pack; restart if you want to play a different pack" model. Which in turn needs new (or at least significantly changed) menus etc to support this.
Isn't this a completely independant issue from any file format change? While I agree that all file format changes should be made in one go, such new ways in accessing levels and level packs shouldn't create any compatibility problems.
With the new file format, NeoLemmix could still read one pack file and load the pack levels from different files. This doesn't require implementing a way to change packs.
On the other hand it should even be possible to implement new menus and moving between level packs with the current file format.
In the time between 1.43n-F and 1.47n, we saw that some users increasingly developed content exclusively for the experimentals. In this case, it wasn't a huge problem, as very few details of the formats changed between experimentals and stable - generally, anything made for the exp version, when the stable release came at most it would need re-testing and some replay fixes. This may very well not be the case when entire new formats are being developed, and the result is going to be one huge mess if that scenario repeats itself in regards to the new formats, which is why I don't want to be releasing them even as experimentals.
I agree, but I got the impression that the current experimental new-file-formats version already works pretty well. Granted, it hasn't yet the new level pack format, but apart from that...