What features, exactly, are you missing from the more recent versions?
There are features in the 2.3.6. version that have been removed in later versions; such as Irish and Scottish provinces and NBRT (that makes the map much more beautiful). From what I've seen, the newer versions do not add any significant improvements to a game focused on North-West Europe (which is my area of interest), except for the HRE culture split, which I've already included in NHO.
To name a few differences, and only really speaking of stuff directly affecting my most focused sphere with HIP:
- Horse Lords compatibility (which is about a lot more than nomads)
- Conclave compatibility (tons of improvements to gameplay depth, diplomacy, warfare, laws, a better feudal model, etc.)
- All the new features and fixes (vanilla and otherwise) and evolution of EMF from almost a year of development [I'd mention SWMH, but you seem to only care that northwestern europe is on the map, to be frank.]
- All the new features and fixes and enhancements done to vanilla itself through 2 major patches
- Compatibility with LTM, likely to become bundled w/ HIP (though that's still pending a vote) too, so definitely back to beautiful SWMH map terrain textures and graphical shaders
- The ability for you to rely upon the HIP team to be able to help sort out bugs into which you run, since the code would be common
... and so much more.
Let me be frank, and please remember that I intend no insult whatsoever:
One ought look at the process of compatching with the latest HIP (just as we constantly compatch with the latest vanilla) as productive: you're actively removing bugs and suboptimal behavior from your sub-mod, and you're actively adding to your mod's content.
TBH, I find your mod ideas interesting, but since you do not do these things, there's no way in hell I'd currently waste my time playing stuff that is officially in the way-outdated category. I'm not going to enjoy what I've actively spent so much time improving far beyond. This is especially true because updating your topic-specific sub-mod to the latest HIP is a lot easier than compatching to the latest vanilla patches and fixing them (which we are doing for you if you'd only accept), as that sort of attitude regarding providing the most enjoyable and polished experience for players that you can is a very ill indicator indeed of the quality to be expected.
But that is just my personal opinion.
I'm not sure, you'd still have the same CB available. I think, if you want a challenge, give the AI some extra powers; crank up the difficulty and give characters like Harald Fairhair and other successful figures "lucky ruler". Another thing, also, it's pretty easy to gather a lot of land as one character, but when your character dies, it's quite a lot hard to keep hold of it all.
Almost all of the changes in EMF since 2.3.6 have been focused upon making the game far more challenging and high-stakes. If you want a challenge, don't play EMF from almost a year ago, but play a recent version.
It is true, HIP isn't what you'd call a hardcore mod, it doesn't significantly increase the difficulty, you have to challenge yourself in various ways. Try starting as a count-tier vassal like Blekinge or another small county.
Turning-up the difficulty will do essentially nothing on that old version of EMF, in contrast to recent versions.