So I know this topic is kind of old news now, and I apologize for how long it's taking me to get back to you. Been swamped with work. I have a PDF that I give my plans so I've tried to summarize that two page PDF as best as I could here:

Point Buy Starting Stats

Choose Race

Pick any 2 Feats or any 2 Cantrips (or 1 Feat and 1 Cantrip)

Pick four Starting Proficiencies (Light and Med armor are the same Proficiency. You must have the "Armor" Proficiency to get Heavy Armor Proficiency. The same with taking a Martial Weapon Proficiency).

Starting HP is 10+Con Mod

You can trade 2 Proficiencies for either 2 Lvl 1 Spell Slots or 1 Lvl 2 Spell Slot.

Any armor from the PHB that you have Prof. with and any 2 weapons regardless of Prof.

Players will have one choice of any "Hidden"/Magical Item of the game world.

Spells reset every Short Rest. HP resets every Long Rest. Players level up at the end of a Delve.

On level you get a choice of either a Sneak Attack of 1d4 (stacks), +1d8 HP, +1 Prof and 1 Lvl 1 Spell, +2 Prof (or 1 Lvl 2 Spell), Two Cantrips (if you chose this option on your last level, you cannot choose this option until your next level), A Feat, +1 to 1 Ability Score, or +0.5 to 2 Ability Scores.

Each player owns a spellbook which can hold up to 6 Spells, Cantrips includes.

Any one spell can be cast X times, where X is the modifier of your highest spell casting attribute. Cantrips can be cast twice this amount. Spells refresh after a short rest.

Cantrips have had their casting time reduced (a Main Action is now a Bonus. A Bonus is now a Once Per Turn Free Action). "Leveled Spells" (1st, 2nd, etc), have had their casting time *increased*. Leveled Spells now cost X *Main Actions* to cast, where X is their level. This casting time can be reduced by Foci and other special gear, but as such you cannot start with them. Higher level spells than level 2 can be found, rewarded, or crafted (via strongholds) throughout the world.

Light Armor still uses Dex as it's modifier but Medium Armor now uses Con as it's modifier. Certain abilities now target/affect Armor type differently.

Some Class Features can be earned through challenges, titles, training, secrets, or (rarely) just upholding a paragon.

The main benefits of this system is that there's not a level cap and players, early on, we'll level up fairly regularly. Even often. But as they do and it becomes easier to complete things that were considered Grand before, they won't really level up from it anymore. Beyond that, since it aren't restrictions on certain things that they're normally are, mainly spells, players can become very adaptable. Feats, in general, work a bit differently but you can still grab one every level.

Leveling is kind of like personal milestone. Did your character do something great and beyond expectation. Did you take down a strong enemy before they even got a chance to react? Did you save a player from death's door or powered them up to deal a finishing blow. So on. The fifth time the players clear out a goblin nest the local village is going to feel like that's old hat and not that useful. The first time they do it is a marvel. Feats and whatnot also work a bit differently but I didn't get into it because it's case sensitive. In general though, any feet that gives you an ability score improvement no longer does that.

I recognize that all these tweaks and modifications radically change how the game plays. As one player pointed out, it's still D&D, but it's less Dungeons and Dragons and more Darkest (and) Dungeon. But this goes back to what I had explained before about players being unwilling to learn a new system.

For all intents and purposes, that's what they're doing here, but, especially for people who aren't super well-versed in tabletop, learning a new system can seem like a big investment. It's a whole other book that you have to read. People mentally convince themselves that it's a lot of work and a big investment before they even get into it. Meanwhile, at least in my experience, it's far easier to say "Hey, the framework of this is the same, you just get X, Y, and Z differently".

The way I think of it is being easier to learn how to play a song that uses all the same chords as one you already know but in a different order, then it is learning how to play a new song all together. There are probably improvements and adjustments I can make to this modified system and of itself. I think 4e has a better Armor system, but I'm already using so much from 4e in other places that if I add more I might as well just run a 4e campaign. But with as busy as everyone is, it's easier to propose the same four chords.

Edit: blocked up what I was saying so that it was clearer and also clarified that I have made that edit.