Okay well. I think it's pretty well agreed that switching to a core player which loads data files (rather than an EXE per game) is the preferred option.
So the next question is - what to do about the editor? There's three possibilities here:
1. Keep the current setup. Some tools may need a bit of reworking, and this may limit what can be done in levels as the Lemmix Editor (from which the NeoLemmix Editor is derived) is quite difficult for me to work out how it does what, and as such, I can't always add new things easily - take a look at how long it took to support custom window orders in any capacity other than "not erasing the data from levels that already have it", for example.
2. Develop a new, all-in-one editor tool (not just levels, but also integrate graphic set editing, etc, into a single app). This is probably my most preferred method. By developing it from scratch, not only will I know exactly how it works and thus be easily able to modify it for new features as needed, but can also make sure it's specifically designed solely with NeoLemmix in mind. The downside is that I probably won't be likely to include support for other formats beyond those of NeoLemmix; while it will be able to import a lot of them, don't expect such a program to be able to edit them and save modified versions.
3. Same as above, but integrate it into the main player EXE. Advantage compared to method 2 is not needing a seperate download, and possibly better integration for playtesting etc; the disadvantage would be that if, say, only the editor has been updated, the whole package will need to be redownloaded. This kind of issue could possibly be minimized with some kind of auto-updater, but I'm not entirely sure about my ability to make such a thing.